- Email: [email protected]
HEART-MUSCLE MAGNESIUM, POTASSIUM, AND ZINC CONCENTRATIONS AFTER SUDDEN DEATH FROM HEART-DISEASE
293
infected patients with increased N.B.T. scores, the predialysis total-leucocyte count was 2-871: 1°13 X 103 per c.mm. (mean ± s.D.) and the post-dialysis level This difference was was 3°95 ±3°14 X 103 per c.mm. not significant (p>0’05, n=40), nor were the predialysis leucocyte-counts significantly different in the infected or non-infected groups (p>0’05, n=140).
The results of our study show that the N.B.T. test can usefully be applied to the urxmic subject as an indicator, often preclinical, of systemic bacterial infection. We thank Prof. A. C. Kennedy for permission to study under his care. We also acknowledge the invaluable assistance of the nursing staff of the dialysis unit.
patients
Requests for reprints should be addressed
to
J.
F. W.
Discussion The
is
established as a useful and rapid screening-test for systemic bacterial infection, although false-positive and false-negative reactions are commonly recognised.10-14 Our results confirm the overall usefulness of the test in the urxmic patient. Wollman et aJ.9 reported normal baseline N.B.T. values in the non-infected urxmic patient and also that such patients retained the capacity for enhanced formazan reduction. The results of the present investigation confirm these findings. However, an analysis of a larger number of results on blood-samples from urxmic subjects has revealed a significant difference between pre and post dialysis N.B.T. scores, a finding which conflicts with previous reports.9 Many factors may be responsible for N.B.T.-test enhancement during dialysis. It has been suggested that a leucotactic/leucocyte maturation factor is activated by contact of blood with dialysis membranes," a theory used to explain reversal of the transient neutropenia known to occur in the first hour of N.B.T. test
dialysis.16-18 Alternatively, dialysis may remove a leucocyte-inhibiting factor, thus permitting phagocytosis to occur.19 Although prolonged intravascular cannulation can increase the N.B.T. score,20 it seems unlikely that the relatively short period of haemodialysis would induce such a change. Endotoxin has been shown to stimulate N.B.T. reduction by polymorphonuclear leucocytes21,22 The observed change in N.B.T. score with dialysis may have been induced by the use of systemic heparin, an agent known to enhance formazan reduction by neutrophils in vitro, in the presence 22 or absence of
endotoxin.23 There
significant increase in leucocyte-count during dialysis, confirming previous observations that a relative neutrophilia 2*,25 follows initial neutropenia in the dialysed subject.16-18 Bacteraemia is common in the regularly dialysed patient.3 The paucity of clinical signs and the absence of leucocytosis may make diagnosis difficult. In the present series an increased pre-dialysis N.B.T. score was observed in 50% of the bacterxmias and fistulae infections at least 24 hoursbefore clinical signs appeared. This test, although non-specific, is therefore useful as an indicator of early infection in the urxmic patient. Coil rupture during dialysis was not associated with was a
increase of the N.B.T. score, an observation which accords with the view that bacterial infection is unto arise from dialysate leak-back in a positivepressure dialyser system.26 Isolated increases of N.B.T. scores may occur due It is therefore recommended to delay in processing. that samples be tested immediately, or, where delay is inevitable, that they be stored at +4’C for not longer than 12 hours.
likely
REFERENCES
now
1.
2. 3. 4.
5.
Montgomerie, J. Z., Kalmanson, G. M., Guze, L. B. Medicine, Baltimore, 1968, 47, 1. Kaslow, R. A., Zellner, S. R. Lancet, 1972, ii, 117. Brunner, F. P., Gurland, H. J., Harlen, H., Scharer, K., Parsons, F. M. Proc. Eur. Dialysis Transplant Ass. 1972, 9, 3. Martin, A. M., Clunie, G. J. A., Tonkin, R. W., Robson, J. S. ibid. 1967, 4, 67. McIntosh, C. S., Petrie, J. C., MacLeod, M. Br. med. J. 1969, iv, 717.
6. 7. 8. 9.
10. 11. 12. 13. 14. 15.
16. 17. 18.
19. 20. 21. 22. 23. 24. 25. 26.
Park, B. H., Fikrig, S. M., Smithwick, E. M. Lancet, 1968, ii, 532. Matula, G., Paterson, P. Y. New Engl. J. Med. 1971, 285, 211. Feigin, R. D., Shackleford, P. G., Choi, S. C., Flake, K. K., Franklin, F. A., Eisenberg, C. S. J. Pediat. 1971, 78, 230. Wollman, M. R., Brennan, B. L., Stenzel, K. H., David, D. S., Lewy, J. E., Ruben, A. L., Miller, D. R. Lancet, 1972, ii, 289. Gordon, A. M., Rowan, R. M., Brown, T., Carson, H. G. J. clin. Path. 1973, 26, 52. Gordon, A. M., Rowan, R. M. Scott. med. J. 1973, 18, 21. Rubinstein, A., Pelet, B. Lancet, 1973, i, 382. Hellum, K. B., Solberg, C. O. ibid. p. 1181. Ramsdale, E. H., Mowbray, J. F. ibid. p. 1246. Gral, T., Schroth, P., DePalma, J. R., Maxwell, M. H. Proc. Eur. Dialysis Transplant Ass. 1969, 6, 312. Smith, E. K. M., Jobbins, K. Br. med. J. 1969, iv, 70. Kaplow, L. S., Goffinet, J. A. J. Am. med. Ass. 1968, 203, 133. Papadimitriou, M., Baker, L. R. I., Seitanidis, B., Sevitt, L. H., Kulatilake, A. E. Br. med. J. 1969, iv, 67. Odeberg, H., Thysell, H. Trans. Am. Soc. artif. intern. Organs (in the press). Freeman, R., King, B. Lancet, 1972, i, 992. Park, B. H., Good, R. A. ibid. 1970, ii, 616. Segal, A. W., Levi, A. J. Medical Research Symposium at University College Hospital, 1973. Ridgway, G. L., Johnson, W. Lancet, 1973, i, 1180. Brubaker, L. H., Nolph, K. D. Blood, 1971, 38, 623. Jensen, D. P., Brubaker, L. H., Nolph, K. D., Johnson, C. A., Nothum, R. J. ibid. 1973, 41, 399. Tierno, P. M., Aboody, R. Nephron, 1969, 6, 110.
HEART-MUSCLE MAGNESIUM, POTASSIUM, AND ZINC CONCENTRATIONS AFTER SUDDEN DEATH FROM HEART-DISEASE BARBARA CHIPPERFIELD
J. R. CHIPPERFIELD Departments of Biochemistry and Chemistry, University of Hull
Heart muscle from subjects who died suddenly from coronary thrombosis or myocardial degeneration contained significantly smaller concentrations of magnesium than heart muscle from subjects who died from other causes. Mean values for the two groups were 172 µg. per g. for the "heart deaths" and 205 µg. per g. for the There was no significant difference in controls. potassium or zinc concentration between the two It is suggested that these results may be groups. related to the high death-rate from cardiovascular disease in soft-water areas.
Sum ary
Introduction THE connection between cardiovascular disease and softness of water-supplies suggests that the mineral
294 content
of
drinking-water affects myocardial
meta-
bolism.1 Crawford and Crawford2 examined necropsy
findings in hard and very soft water areas and demonstrated that the " water factor " probably influenced the myocardium rather than arterial disease. They also showed that for young accident victims there was less calcium and magnesium in the coronary arteries of men from soft-water areas. Serum calcium and magnesium were lower in inhabitants of a town using soft water,3and serum and erythrocytic calcium and magnesium were significantly decreased in congestive heart-disease before treatment. Serum-magnesium is often low in patients undergoing diuretic therapy for heart-failure,5 and this is thought to be a result of the drug treatment. Sodium and potassium concentrations in skeletal muscle were altered in heart-disease6and there was some evidence that sodium and potassium in the heart muscle itself might be affected. Since the increase in deaths from heart-disease in soft-water areas has been found to be due entirely to an excess of sudden deaths,’ we decided to measure concentrations of some cations in the heart muscle after sudden death from heart-disease. Samples all came from coroners’ necropsies: one group in which the cause of death proved to be coronary thrombosis or myocardial degeneration, and another group of individuals from the same area in whom sudden death was not due to heart-disease. Magnesium levels were measured because this cation is very important in normal heart contraction. Potassium is the chief intracellular cation, and its concentration generally changes when magnesium concentration is altered.8 We also measured zinc as a divalent cation similar to magnesium, whose uptake is said to be influenced by calcium in water 9 Materials and Methods
Samples of heart muscle were collected after necropsy from the city mortuary and stored, sealed at -20°C, until they were analysed. The muscle was freed from obvious fat and blood-vessels. About 4 g. samples were accurately weighed and wet ashed in Kjeldahl flasks using 10 ml. of the 3/1/1 nitric acid/perchloric acid/sulphuric acid mixture recommended by Christian and Feldman.l0
The remaining solutions were made up to 25 ml. with ion-free water. Analyses for K+, Mg2+, and Zn2+ were carried out using a Southern Analytical Model 1750 atomicabsorption spectrophotometer.10 The samples were diluted suitably with water and sprayed into an air/propane flame. The absorbances at 404-4 nm. (K+), 285-2 nm. (Mg2+), and 213-9 nm. (Zn2+) were measured and standard solutions of potassium nitrate, magnesium sulphate, and zinc sulphate were used to obtain calibration curves. All dilute solutions were stored in polyethylene bottles to prevent adsorption of metal ions on to glass surfaces. It was necessary to add lanthanum nitrate (500 p.p.m. La3+) to the solutions used for Mg2+ measurements to counteract interference from other ions present. There were no problems with interference for K+ or Zn2+.
Results The results
given in tables I and n. There was difference between the two groups for significant zinc and potassium concentrations. There was a between difference significant magnesium concentrations in the two groups (t=261, 0.01
no
statistically significant. There was possibly a slight tendency in the controls for the magnesium concentration to increase with age (see accompanying figure). This was probably due to the dehydration which occurs with age. The
TABLE I-SUDDEN DEATHS FROM HEART-DISEASE
295 TABLE II--CONTROLS
Graph of Mg2+ concentration against
age for
heart deaths
and controls.
The line is the best fit for the controls.
increase was not very great, and would be expected to reduce the observed difference, since the mean age of the subjects who died from heart-disease was higher than that of the controls. Discussion There was a highly significant decrease in concentration of magnesium ions in the group who died suddenly from heart-disease. This might, of cours.e, have been caused by the coronary thrombosis or myocardial degeneration, but this is unlikely in view of the experimental studies of Case 11 and other workers. In conditions of anoxia in dogs, the heart released lactate, phosphate, and potassium ions. It was suggested that magnesium or calcium might also leave the myocardium, because the potassium was not sufficient to neutralise the lactate and phosphate leaving the heart. We may have had an anoxic area of myocardium in one sample in the three subjects in whom duplicate determinations of magnesium and potassium did not agree. If this were true, it would be evidence of magnesium release from the myocardium in anoxia and would deserve further investigation. The constancy of potassium concentration in all the other samples suggests that the muscle was not significantly anoxic. Possibly, the magnesium concen-
tration falls first and is later followed by the potassium concentration. Whatever the cause of the decrease in magnesium, it is bound to be deleterious to the functioning of the heart. The actomyosin adenosine triphosphatase of the heart, which provides the contractile force, is activated by magnesium ions.12, 13 Deficiency of magnesium has also been associated with increased sensitivity of the heart to development of arrhythmias.14-16 Therapy with magnesium salts has been shown to improve survival after myocardial infarction.15 It is perhaps surprising, in view of this decrease in magnesium, that no correlation has been found between increased magnesium concentration in drinkingwater and decreased death-rate from cardiovascular disease.’ If a decrease in magnesium in the heart is connected in any way with ingestion of soft water, the effect must be indirect. In their analysis of lead deposition in bone, Crawford and Clayton17 suggested that the increased lead found in soft-water supplies might possibly replace magnesium in the heart muscle. This, together with our observations on the highly significant decrease in magnesium in sudden heart deaths, suggests that magnesium concentrations in the heart muscle of individuals from hard and soft water areas might demonstrate a fall in magnesium concentration in those from the soft-water areas. We thank the coroner, police surgeons, and mortuary attendants for their cooperation in the collection of tissues. Mr B. N. Somers, Miss C. Wrangham, and Mr P. A. Trimby assisted in the estimations. Dr N. Angus allowed us to use the atomic absorption spectrometer in the Department of Geology for the zinc estimations.
Requests Department
for of
reprints should be addressed to B. C., Biochemistry, University of Hull, Hull
HU6 7RX. REFERENCES
Crawford, M. D., Gardner, M. J., Morris, J. N. Br. med. Bull. 1971, 27, 21. 2. Crawford, T., Crawford, M. D. Lancet, 1967, i, 229. 3. Bierenbaum, M. L., Fleischmann, A. I., Dunn, J. P., Belk, H. D., Storter, B. M. Israel J. med. Sci. 1969, 5, 657. 4. Seller, R. H., Ramirez, O., Brest, A. N., Moyer, J. H. Am. J. Cardiol. 1966, 17, 786. 5. Lim, P., Jacob, E. Br. med. J. 1972, iii, 620. 6. Flear, C. T. G. Ann. N.Y. Acad. Sci. 1969, 156, 421. 7. Anderson, T. W., Le Riche, W. H., MacKay, J. S. New Engl. J. Med. 1969, 280, 805. 8. Whang, R., Welt, L. G. J. clin. Invest. 1963, 42, 305. 9. Schroeder, H. A. J. chron. Dis. 1965, 18, 217. 1.
-
296 TABLE I-BOUTS OF SCRATCHING DURING EACH STAGE OF SLEEP
Preliminary Communication SCRATCHING DURING SLEEP
J. A. SAVIN
W. D. PATERSON IAN OSWALD
Department of Dermatology, Royal Infirmary, and University Department of Psychiatry, Edinburgh Four patients with atopic eczema were studied throughout the night, while was monitored for electrophysiological varisleep ables. Scratching occurred during all stages of sleep, often without change of stage. The pattern of varied in different the scratching stages. The frebouts of and of the scratching during quency length sleep offer objective measures of skin itchiness. The technique described may be suitable for use in trials of systemic antipruritic agents.
Summary
INTRODUCTION
ITCHING is difficult to investigate, since changes can only be judged subjectively by the patient himself. Most trials of antipruritic drugs depend upon this judgment; but the method may not be valid if the drug to be studied has other actions. For example, trimeprazine may reduce itching directly, but it might also, through a tranquillising effect, alter the patient’s view of the seriousness of his itching. There are other difficulties: any tablet given to an itching patient may have a pronounced placebo effect 1, 2; and studies of experimentally induced itching in animalsmay not be applicable to human disease. We have chosen to study scratching during sleep, since many of the variables which affect scratching during wakefulness are eliminated. Our aims were to establish the timing of scratching in relation to the different stages of sleep, and to see if a quantitative and objective approach to scratching was
possible.
fixed with tape above and below each
outer
canthus for
diagonal bipolar E.o.G. detection and two below the chin for E.M.G. recording. In addition, two electrodes were side of the ventral surface of each to the ulnar taped forearm to pick up muscle potentials from scratching movements; the effectiveness of these was checked before each night’s recording. A paper speed of 15 mm. per second was used with time constants of 0’3 second except for 0-01 for submental E.M.G. Each patient slept alone in a comfortable, ventilated, and sound-attenuated bedroom remote from all recordings. Recordings were analysed in 20 second periods in terms of wakefulness and the usual stages of sleep: namely, orthodox (no rapid eye movements) (N.R.E.M.) sleep stages 1, 2, 3, and 4 and paradoxical (rapid eye movements) (R.E.M.) sleep.4 Special note was made of the sleep stage in which each scratching bout arose and of the stage in which it ended. The duration of each bout of scratching was measured from the electrical trace. RESULTS
PATIENTS AND METHODS
patients with longstanding and severe studied in the sleep laboratory. Three atopic patients were studied for 1 night each and the fourth Three had taken no systemic was studied for 2 nights. medication for the preceding week; one (patient 4, table I) took her usual dose of trimeprazine (10 mg.) on retiring. Four
Recordings were made of all-night electroencephalogram (E.E.G.), electro-oculogram (E.O.G.), submental electromyogram (E.M.G.), and muscle potentials from both foreSilver electrodes containing electrode jelly were arms. placed on the scalp in midline parietal and occipital positions (Cz and 0.for recording E.E.G. ; others were
adult
eczema were
Scratching was seen both on closed-circuit television and on the paper record. It occurred in all stages of orthodox and paradoxical sleep. We observed, in the four patients, a total of 482 distinct bouts of scratching during sleep. Table I shows the distribution of these bouts classified
No local treatment had been used for 24 hours before the period of observation. They slept in conditions of low illumination, allowing observation on closed-circuit television, and all movements, including scratching, were noted on the moving-paper record.
Christian, G. D., Feldman, F. J. Atomic Absorption SpectroscopyApplications in Agriculture, Biology and Medicine; p. 193. New York, 1970. 11. Case, R. B. Cardiology, 1971/72, 56, 245. 12. Alpert, N. R., Gordon, M. S. Am. J. Physiol. 1962, 202, 940. 13. Katz, A. M. Physiol. Rev. 1970, 50, 63. 14. Seller, R. H. Am. Heart J. 1971, 82, 551. 15. Wüstenberg, P.-W. Z. ges. inn. Med. 1972, 27, 45. 16. Wacker, W. E. C., Parisi, A. F. New Engl. J. Med. 1968, 278, 772. 17. Crawford, M. D., Clayton, D. G. Br. med. J. 1973, ii, 21. 10.
Fig. 1-Average frequency with which bouts of scratching started during each stage of sleep.
infected patients with increased N.B.T. scores, the predialysis total-leucocyte count was 2-871: 1°13 X 103 per c.mm. (mean ± s.D.) and the post-dialysis level This difference was was 3°95 ±3°14 X 103 per c.mm. not significant (p>0’05, n=40), nor were the predialysis leucocyte-counts significantly different in the infected or non-infected groups (p>0’05, n=140).
The results of our study show that the N.B.T. test can usefully be applied to the urxmic subject as an indicator, often preclinical, of systemic bacterial infection. We thank Prof. A. C. Kennedy for permission to study under his care. We also acknowledge the invaluable assistance of the nursing staff of the dialysis unit.
patients
Requests for reprints should be addressed
to
J.
F. W.
Discussion The
is
established as a useful and rapid screening-test for systemic bacterial infection, although false-positive and false-negative reactions are commonly recognised.10-14 Our results confirm the overall usefulness of the test in the urxmic patient. Wollman et aJ.9 reported normal baseline N.B.T. values in the non-infected urxmic patient and also that such patients retained the capacity for enhanced formazan reduction. The results of the present investigation confirm these findings. However, an analysis of a larger number of results on blood-samples from urxmic subjects has revealed a significant difference between pre and post dialysis N.B.T. scores, a finding which conflicts with previous reports.9 Many factors may be responsible for N.B.T.-test enhancement during dialysis. It has been suggested that a leucotactic/leucocyte maturation factor is activated by contact of blood with dialysis membranes," a theory used to explain reversal of the transient neutropenia known to occur in the first hour of N.B.T. test
dialysis.16-18 Alternatively, dialysis may remove a leucocyte-inhibiting factor, thus permitting phagocytosis to occur.19 Although prolonged intravascular cannulation can increase the N.B.T. score,20 it seems unlikely that the relatively short period of haemodialysis would induce such a change. Endotoxin has been shown to stimulate N.B.T. reduction by polymorphonuclear leucocytes21,22 The observed change in N.B.T. score with dialysis may have been induced by the use of systemic heparin, an agent known to enhance formazan reduction by neutrophils in vitro, in the presence 22 or absence of
endotoxin.23 There
significant increase in leucocyte-count during dialysis, confirming previous observations that a relative neutrophilia 2*,25 follows initial neutropenia in the dialysed subject.16-18 Bacteraemia is common in the regularly dialysed patient.3 The paucity of clinical signs and the absence of leucocytosis may make diagnosis difficult. In the present series an increased pre-dialysis N.B.T. score was observed in 50% of the bacterxmias and fistulae infections at least 24 hoursbefore clinical signs appeared. This test, although non-specific, is therefore useful as an indicator of early infection in the urxmic patient. Coil rupture during dialysis was not associated with was a
increase of the N.B.T. score, an observation which accords with the view that bacterial infection is unto arise from dialysate leak-back in a positivepressure dialyser system.26 Isolated increases of N.B.T. scores may occur due It is therefore recommended to delay in processing. that samples be tested immediately, or, where delay is inevitable, that they be stored at +4’C for not longer than 12 hours.
likely
REFERENCES
now
1.
2. 3. 4.
5.
Montgomerie, J. Z., Kalmanson, G. M., Guze, L. B. Medicine, Baltimore, 1968, 47, 1. Kaslow, R. A., Zellner, S. R. Lancet, 1972, ii, 117. Brunner, F. P., Gurland, H. J., Harlen, H., Scharer, K., Parsons, F. M. Proc. Eur. Dialysis Transplant Ass. 1972, 9, 3. Martin, A. M., Clunie, G. J. A., Tonkin, R. W., Robson, J. S. ibid. 1967, 4, 67. McIntosh, C. S., Petrie, J. C., MacLeod, M. Br. med. J. 1969, iv, 717.
6. 7. 8. 9.
10. 11. 12. 13. 14. 15.
16. 17. 18.
19. 20. 21. 22. 23. 24. 25. 26.
Park, B. H., Fikrig, S. M., Smithwick, E. M. Lancet, 1968, ii, 532. Matula, G., Paterson, P. Y. New Engl. J. Med. 1971, 285, 211. Feigin, R. D., Shackleford, P. G., Choi, S. C., Flake, K. K., Franklin, F. A., Eisenberg, C. S. J. Pediat. 1971, 78, 230. Wollman, M. R., Brennan, B. L., Stenzel, K. H., David, D. S., Lewy, J. E., Ruben, A. L., Miller, D. R. Lancet, 1972, ii, 289. Gordon, A. M., Rowan, R. M., Brown, T., Carson, H. G. J. clin. Path. 1973, 26, 52. Gordon, A. M., Rowan, R. M. Scott. med. J. 1973, 18, 21. Rubinstein, A., Pelet, B. Lancet, 1973, i, 382. Hellum, K. B., Solberg, C. O. ibid. p. 1181. Ramsdale, E. H., Mowbray, J. F. ibid. p. 1246. Gral, T., Schroth, P., DePalma, J. R., Maxwell, M. H. Proc. Eur. Dialysis Transplant Ass. 1969, 6, 312. Smith, E. K. M., Jobbins, K. Br. med. J. 1969, iv, 70. Kaplow, L. S., Goffinet, J. A. J. Am. med. Ass. 1968, 203, 133. Papadimitriou, M., Baker, L. R. I., Seitanidis, B., Sevitt, L. H., Kulatilake, A. E. Br. med. J. 1969, iv, 67. Odeberg, H., Thysell, H. Trans. Am. Soc. artif. intern. Organs (in the press). Freeman, R., King, B. Lancet, 1972, i, 992. Park, B. H., Good, R. A. ibid. 1970, ii, 616. Segal, A. W., Levi, A. J. Medical Research Symposium at University College Hospital, 1973. Ridgway, G. L., Johnson, W. Lancet, 1973, i, 1180. Brubaker, L. H., Nolph, K. D. Blood, 1971, 38, 623. Jensen, D. P., Brubaker, L. H., Nolph, K. D., Johnson, C. A., Nothum, R. J. ibid. 1973, 41, 399. Tierno, P. M., Aboody, R. Nephron, 1969, 6, 110.
HEART-MUSCLE MAGNESIUM, POTASSIUM, AND ZINC CONCENTRATIONS AFTER SUDDEN DEATH FROM HEART-DISEASE BARBARA CHIPPERFIELD
J. R. CHIPPERFIELD Departments of Biochemistry and Chemistry, University of Hull
Heart muscle from subjects who died suddenly from coronary thrombosis or myocardial degeneration contained significantly smaller concentrations of magnesium than heart muscle from subjects who died from other causes. Mean values for the two groups were 172 µg. per g. for the "heart deaths" and 205 µg. per g. for the There was no significant difference in controls. potassium or zinc concentration between the two It is suggested that these results may be groups. related to the high death-rate from cardiovascular disease in soft-water areas.
Sum ary
Introduction THE connection between cardiovascular disease and softness of water-supplies suggests that the mineral
294 content
of
drinking-water affects myocardial
meta-
bolism.1 Crawford and Crawford2 examined necropsy
findings in hard and very soft water areas and demonstrated that the " water factor " probably influenced the myocardium rather than arterial disease. They also showed that for young accident victims there was less calcium and magnesium in the coronary arteries of men from soft-water areas. Serum calcium and magnesium were lower in inhabitants of a town using soft water,3and serum and erythrocytic calcium and magnesium were significantly decreased in congestive heart-disease before treatment. Serum-magnesium is often low in patients undergoing diuretic therapy for heart-failure,5 and this is thought to be a result of the drug treatment. Sodium and potassium concentrations in skeletal muscle were altered in heart-disease6and there was some evidence that sodium and potassium in the heart muscle itself might be affected. Since the increase in deaths from heart-disease in soft-water areas has been found to be due entirely to an excess of sudden deaths,’ we decided to measure concentrations of some cations in the heart muscle after sudden death from heart-disease. Samples all came from coroners’ necropsies: one group in which the cause of death proved to be coronary thrombosis or myocardial degeneration, and another group of individuals from the same area in whom sudden death was not due to heart-disease. Magnesium levels were measured because this cation is very important in normal heart contraction. Potassium is the chief intracellular cation, and its concentration generally changes when magnesium concentration is altered.8 We also measured zinc as a divalent cation similar to magnesium, whose uptake is said to be influenced by calcium in water 9 Materials and Methods
Samples of heart muscle were collected after necropsy from the city mortuary and stored, sealed at -20°C, until they were analysed. The muscle was freed from obvious fat and blood-vessels. About 4 g. samples were accurately weighed and wet ashed in Kjeldahl flasks using 10 ml. of the 3/1/1 nitric acid/perchloric acid/sulphuric acid mixture recommended by Christian and Feldman.l0
The remaining solutions were made up to 25 ml. with ion-free water. Analyses for K+, Mg2+, and Zn2+ were carried out using a Southern Analytical Model 1750 atomicabsorption spectrophotometer.10 The samples were diluted suitably with water and sprayed into an air/propane flame. The absorbances at 404-4 nm. (K+), 285-2 nm. (Mg2+), and 213-9 nm. (Zn2+) were measured and standard solutions of potassium nitrate, magnesium sulphate, and zinc sulphate were used to obtain calibration curves. All dilute solutions were stored in polyethylene bottles to prevent adsorption of metal ions on to glass surfaces. It was necessary to add lanthanum nitrate (500 p.p.m. La3+) to the solutions used for Mg2+ measurements to counteract interference from other ions present. There were no problems with interference for K+ or Zn2+.
Results The results
given in tables I and n. There was difference between the two groups for significant zinc and potassium concentrations. There was a between difference significant magnesium concentrations in the two groups (t=261, 0.01
no
statistically significant. There was possibly a slight tendency in the controls for the magnesium concentration to increase with age (see accompanying figure). This was probably due to the dehydration which occurs with age. The
TABLE I-SUDDEN DEATHS FROM HEART-DISEASE
295 TABLE II--CONTROLS
Graph of Mg2+ concentration against
age for
heart deaths
and controls.
The line is the best fit for the controls.
increase was not very great, and would be expected to reduce the observed difference, since the mean age of the subjects who died from heart-disease was higher than that of the controls. Discussion There was a highly significant decrease in concentration of magnesium ions in the group who died suddenly from heart-disease. This might, of cours.e, have been caused by the coronary thrombosis or myocardial degeneration, but this is unlikely in view of the experimental studies of Case 11 and other workers. In conditions of anoxia in dogs, the heart released lactate, phosphate, and potassium ions. It was suggested that magnesium or calcium might also leave the myocardium, because the potassium was not sufficient to neutralise the lactate and phosphate leaving the heart. We may have had an anoxic area of myocardium in one sample in the three subjects in whom duplicate determinations of magnesium and potassium did not agree. If this were true, it would be evidence of magnesium release from the myocardium in anoxia and would deserve further investigation. The constancy of potassium concentration in all the other samples suggests that the muscle was not significantly anoxic. Possibly, the magnesium concen-
tration falls first and is later followed by the potassium concentration. Whatever the cause of the decrease in magnesium, it is bound to be deleterious to the functioning of the heart. The actomyosin adenosine triphosphatase of the heart, which provides the contractile force, is activated by magnesium ions.12, 13 Deficiency of magnesium has also been associated with increased sensitivity of the heart to development of arrhythmias.14-16 Therapy with magnesium salts has been shown to improve survival after myocardial infarction.15 It is perhaps surprising, in view of this decrease in magnesium, that no correlation has been found between increased magnesium concentration in drinkingwater and decreased death-rate from cardiovascular disease.’ If a decrease in magnesium in the heart is connected in any way with ingestion of soft water, the effect must be indirect. In their analysis of lead deposition in bone, Crawford and Clayton17 suggested that the increased lead found in soft-water supplies might possibly replace magnesium in the heart muscle. This, together with our observations on the highly significant decrease in magnesium in sudden heart deaths, suggests that magnesium concentrations in the heart muscle of individuals from hard and soft water areas might demonstrate a fall in magnesium concentration in those from the soft-water areas. We thank the coroner, police surgeons, and mortuary attendants for their cooperation in the collection of tissues. Mr B. N. Somers, Miss C. Wrangham, and Mr P. A. Trimby assisted in the estimations. Dr N. Angus allowed us to use the atomic absorption spectrometer in the Department of Geology for the zinc estimations.
Requests Department
for of
reprints should be addressed to B. C., Biochemistry, University of Hull, Hull
HU6 7RX. REFERENCES
Crawford, M. D., Gardner, M. J., Morris, J. N. Br. med. Bull. 1971, 27, 21. 2. Crawford, T., Crawford, M. D. Lancet, 1967, i, 229. 3. Bierenbaum, M. L., Fleischmann, A. I., Dunn, J. P., Belk, H. D., Storter, B. M. Israel J. med. Sci. 1969, 5, 657. 4. Seller, R. H., Ramirez, O., Brest, A. N., Moyer, J. H. Am. J. Cardiol. 1966, 17, 786. 5. Lim, P., Jacob, E. Br. med. J. 1972, iii, 620. 6. Flear, C. T. G. Ann. N.Y. Acad. Sci. 1969, 156, 421. 7. Anderson, T. W., Le Riche, W. H., MacKay, J. S. New Engl. J. Med. 1969, 280, 805. 8. Whang, R., Welt, L. G. J. clin. Invest. 1963, 42, 305. 9. Schroeder, H. A. J. chron. Dis. 1965, 18, 217. 1.
-
296 TABLE I-BOUTS OF SCRATCHING DURING EACH STAGE OF SLEEP
Preliminary Communication SCRATCHING DURING SLEEP
J. A. SAVIN
W. D. PATERSON IAN OSWALD
Department of Dermatology, Royal Infirmary, and University Department of Psychiatry, Edinburgh Four patients with atopic eczema were studied throughout the night, while was monitored for electrophysiological varisleep ables. Scratching occurred during all stages of sleep, often without change of stage. The pattern of varied in different the scratching stages. The frebouts of and of the scratching during quency length sleep offer objective measures of skin itchiness. The technique described may be suitable for use in trials of systemic antipruritic agents.
Summary
INTRODUCTION
ITCHING is difficult to investigate, since changes can only be judged subjectively by the patient himself. Most trials of antipruritic drugs depend upon this judgment; but the method may not be valid if the drug to be studied has other actions. For example, trimeprazine may reduce itching directly, but it might also, through a tranquillising effect, alter the patient’s view of the seriousness of his itching. There are other difficulties: any tablet given to an itching patient may have a pronounced placebo effect 1, 2; and studies of experimentally induced itching in animalsmay not be applicable to human disease. We have chosen to study scratching during sleep, since many of the variables which affect scratching during wakefulness are eliminated. Our aims were to establish the timing of scratching in relation to the different stages of sleep, and to see if a quantitative and objective approach to scratching was
possible.
fixed with tape above and below each
outer
canthus for
diagonal bipolar E.o.G. detection and two below the chin for E.M.G. recording. In addition, two electrodes were side of the ventral surface of each to the ulnar taped forearm to pick up muscle potentials from scratching movements; the effectiveness of these was checked before each night’s recording. A paper speed of 15 mm. per second was used with time constants of 0’3 second except for 0-01 for submental E.M.G. Each patient slept alone in a comfortable, ventilated, and sound-attenuated bedroom remote from all recordings. Recordings were analysed in 20 second periods in terms of wakefulness and the usual stages of sleep: namely, orthodox (no rapid eye movements) (N.R.E.M.) sleep stages 1, 2, 3, and 4 and paradoxical (rapid eye movements) (R.E.M.) sleep.4 Special note was made of the sleep stage in which each scratching bout arose and of the stage in which it ended. The duration of each bout of scratching was measured from the electrical trace. RESULTS
PATIENTS AND METHODS
patients with longstanding and severe studied in the sleep laboratory. Three atopic patients were studied for 1 night each and the fourth Three had taken no systemic was studied for 2 nights. medication for the preceding week; one (patient 4, table I) took her usual dose of trimeprazine (10 mg.) on retiring. Four
Recordings were made of all-night electroencephalogram (E.E.G.), electro-oculogram (E.O.G.), submental electromyogram (E.M.G.), and muscle potentials from both foreSilver electrodes containing electrode jelly were arms. placed on the scalp in midline parietal and occipital positions (Cz and 0.for recording E.E.G. ; others were
adult
eczema were
Scratching was seen both on closed-circuit television and on the paper record. It occurred in all stages of orthodox and paradoxical sleep. We observed, in the four patients, a total of 482 distinct bouts of scratching during sleep. Table I shows the distribution of these bouts classified
No local treatment had been used for 24 hours before the period of observation. They slept in conditions of low illumination, allowing observation on closed-circuit television, and all movements, including scratching, were noted on the moving-paper record.
Christian, G. D., Feldman, F. J. Atomic Absorption SpectroscopyApplications in Agriculture, Biology and Medicine; p. 193. New York, 1970. 11. Case, R. B. Cardiology, 1971/72, 56, 245. 12. Alpert, N. R., Gordon, M. S. Am. J. Physiol. 1962, 202, 940. 13. Katz, A. M. Physiol. Rev. 1970, 50, 63. 14. Seller, R. H. Am. Heart J. 1971, 82, 551. 15. Wüstenberg, P.-W. Z. ges. inn. Med. 1972, 27, 45. 16. Wacker, W. E. C., Parisi, A. F. New Engl. J. Med. 1968, 278, 772. 17. Crawford, M. D., Clayton, D. G. Br. med. J. 1973, ii, 21. 10.
Fig. 1-Average frequency with which bouts of scratching started during each stage of sleep.