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The alteration of surface charge characteristics of the vascular system by oral contraceptive steroids
THE ALTERATION OF SURFACE CHARGE CHARACTERISTICS OF THE VASCULAR SYSTEM BY ORAL CONTRACEPTIVE STEROIDS S. Srinivasan*, J. Solash, A. Redner, C. Moser, D. Farhangian, T.R. Lucas, E. Ateyeh, Jr., C.T. McCOol, D. weber, S.I. Puvan+, J.R. Jones++ and P.N. Sawyer Electrochemical and Biophysical Laboratories, Department of Surgery, State University of New York, Downstate Medical Center, Brooklyn, New York 11203 ABSTRACT One of the serious side effects of the oral contraceptives is that of thromboembolism. When the surfaces of the blood vessel wall and of blood cells become less negatively Our precharged, conditions prone to thrombosis develop. vious studies revealed that anticoagulants increase or maintain the negative charge densities of these vascular components while procoagulants have the opposite effect. In the present work, the effects of norethindrone and of mestranol on the surface charge characteristics of the vascular system were determined using electrokinetic (streaming potential, electroosmosis, electrophoresis) techniques. Also, electrophoretic mobility measurements were made on platelets from women on and off the pill (containing mestranol and norethindrone). Mestranol and norethindrone, alone and in combination, decreased the negative surface charge densities of the blood vessel wall and of blood Platelets from women taking anti-pregnancy hormones cells. had significantly lower electrophoretic mobilities than those not taking them. The studies confirm the procoagulant action of the hormones in the pill.
*
Present address: Colorado 80302
+
Present address: Department of Obstetrics and Gynecology, University Of Malaysia, Kuala Lumpar, Malaysia
I.B.M.,
P.O. Box 1900, Boulder,
++ Department of Obstetrics and Gynecology, SUNY, Downstate Medical Center, Brooklyn, New York 11203 Accepted
for
publication
MARCH
1974
VOL.
January
9 NO. 3
15,
1974
291
CONTRACEPTION
INTRODUCTION Recent epidemiological studies (l-3) have indicated that women who use oral contraceptive steroids develop a higher incidence of thromboembolic disease than women who do not use them. Many recent studies have linked the use of the oral contraceptive drugs with abnormalities in cardiovascular function (4-6), plasma protein and blood coagulation factor levels (7,8), and platelet behavior (9-12). According to our work, it is very probable that oral contraceptives alter the charge characteristics of the vascular system. Work from this laboratory (13,14) indicates that alteration in the charge characteristics at the vascular interface may be linked to the thromboembolic phenomena observed in users of oral contraceptives (l-3). The characteristic surface potential of the vascular interface or blood cells may be measured by use of electrokinetic techniques. From our previous studies (15-20), it follows that: (a) under normal conditions, blood vessel intima and blood cell membranes are homogeneously negatively charged and demonstrate a negative zeta potential across blood vessel wall or cell surface-solution interface (15-20); (b) injury to blood vessels reduces the magnitude of the zeta potential (21,22); and (c) antithrombotic drugs increase the magnitude of the zeta potential while procoagulants decrease it (15-20). The techniques which we have been employing include measurement of the electrophoretic mobility of blood cells (18), streaming potential (15,16,18), and electroosmotic (15,16) measurements on blood vessels. The electrophoretic mobility of a particle or blood cell is directly proportional to its zeta potential; from the results of electroosmosis and streaming potential measurements, the zeta potential can be calculated easily. In the present investigation, we tried to determine the effects of an oral contraceptive preparation as well as of its constituent hormones on: (a) the electrophoretic' mobility of platelets; (b) the zeta potentials across blood vessel-solution interfaces as measured by electroosmosis; and (c) correlation of these in vitro surface charge effects with their action on an intact, in vivo For the latter study, the current clotting system. induced occlusion time in rat mesentery vessels was used
292
MARCH
1974 VOL. 9 NO. 3
CONTRACEPTION
as a measure steroids.
of the coagulant
METHODS
effect
of the contraceptive
AND MATERIALS
Electrophoresis Human platelets were obtained from female donors who Blood was drawn into were not taking oral contraceptives. glass tubes, containing l/10 volume of 3.2% sodium citrate solution, and centrifuged at 100 x g for 12 minutes. The supernatant plasma (platelet rich plasma) was diluted with Krebs (Ca++ free) solution (20) (1.5:5) containing varying amounts of the contraceptive steroids and incubated at 25-C for 1 hour in siliconized glass tubes before electrophorePlatelets were also tic mobility measurements were made. obtained from women who were taking a mestranol/norethindrone combination pill. All electrophoretic mobility measurements were performed using a Seaman micro-electrophoresis cell* at 37-C. The cell and platinized/platinum electrodes were thoroughly cleaned in a cont. sulfuric acid/cone. nitric acid (90/10) mixture and rinsed very well with triple distilled water, saturated sodium bicarbonate, and finally with triple distilled water. The plati?ized/platinum electrodes had a geometric area of 7.5 cm . Platelet movement was timed using a stopwatch and the eyepiece graticule. The average transit time of human platelets in one direction was approximately 11-12 sec. and at least 10 platelets were observed (5 in each direction) for each run. Electroosmosis Electroosmotic measurements were performed on sections of canine aorta which were removed from normal healthy dogs. The facia was removed from the advential side of the vessel and the aorta was then clamped between
* Micro-electrophoresis apparatus Bottisham, canibridge, England.
MARCH
1974 VOL. 9 NO. 3
obtained
from Rank Bros.,
293
CONTRACEPTION
each half cell (Figure 1). The cell was carefully filled with Izrebs solution which contained varying quantities of estrogen or progestin. The cell was then fitted with two silver/silver chloride electrodes: care was taken to exThe initial and clude all air bubbles from the system. final volume measurements were recorded from the manometers before and after a current of 1OmA was passed for The current was reversed and the volume three minutes. measurements recorded again after a period of three minThis procedure was repeated twice more (each elecutes. trode cathodic three times). This technique has been fully described elsewhere (23-25). Current
induced
occlusion
times
in rat mesenteric
vessels
Female Wistar rats weighing between 130 grams (small rats) and 225-275 grams (large rats) received an IP injection of a combination of mestranol/norethindrone daily for lo-12 days. All injections of contraceptives were made in the morning and on the afternoon of the last injection, the current induced occlusion time was measured. The rat was anesthetized with pentothal (IP injection), a midline incision was made and the mesoappendix extracted. The extracted portion of the mesoappendix was observed microscopically while a current of lO)(A was passed across the tissue by means of a suitable power supply and two microelectrodes. The extracted tissues of the mesoappendix were bathed in physiologic saline (37'C) to prevent necrosis and shock. Materials The mestranol and norethindrone used in this study were graciously supplied by Ortho Pharmaceutical Company. Pentothal sodium was obtained from Abbott Laboratories. RESULTS In Figure 2, the results of the effects of oral contraceptives on the electrophoretic mobility of platelets, which were incubated for one hour in Krebs (Ca++ free) solution containing varying quantities of oral contraceptives, are presented. Under these conditions, the changes in electrophoretic mobility are small and not highly significant (PeO.1). However, platelets which were obtained from women who had been taking oral contra-
294
MARCH
1974
VOL.
9 NO. 3
CONTRACEPTION Anode
Figure
MARCH
1:
Schematic
Cathode
of electroosmosis
1974 VOL. 9 NO. 3
apparatus.
295
CONTRACEPTION
Figure 2:
296
Results of platelet electrophoretic mobility studies. Krebs solution containing mestranol, norethindrone and a combination of mestranol and norethindrone were allowed to incubate with platelet rich plasma for 1 hour prior to measurement. Electrophoretic mobility of platelets obtained from women taking a mestranol/norethindrone "pill" is also shown.
MARCH
1974 VOL. 9 NO. 3
CONTRACEPTION
ceptives for at least 6 months, showed much in electrophoretic mobility (Figure 2).
larger changes
In Table I, the values for the zeta potentials across the blood vessel wall-Krebs solution (containing contraceptives) interface are compared to control values (Krebs solution without contraceptives). A test of the coagulant (pro or anti) ability of these compounds, in The effects of the oral contra%pwas necessary. a, tive steroids on the current induced occlusion times of The electrophoretic rat mesentery vessels were measured. mobility data and the electroosmosis data indicate that oral contraceptives may act as mild procoagulants -in vitro. The results of the current induced occlusion times in rat mesoappendix vessels (Table II) shows that in this system, the contraceptive steroids exert a strong procoagulant action. DISCUSSION The -in vitro electrokinetic experiments reveal that contraceptive steroids increase the magnitude of the zeta potential of both human platelets and canine blood vessel A strong procoagulant effect of these compounds walls. was exhibited -in vivo in the rat mesentery system. By extrapolation of the data obtained in non-human systems, one can tentatively conclude that the oral contraceptive steroids decrease the magnitude of the zeta potential of the elements of the vascular tree and, therefore, exert a procoagulant effect on the human vascular system by lowering the natural repulsive force between platelets and vessel walls. The oral contraceptives probably exert this procoagulant effect by their adsorption from blood on the surface of vessel walls and platelets with a consequent lowering of the zeta potential. The precise mechanism of the effect on the zeta potential by the contraceptives remains unknown. This could be a result of simple adsorption on the vascular elements or could result from some subtle metabolic change caused after adsorption on the vascular tree. The fact that platelet sensitivity toward ADP, exhibited by women on oral contraceptives, disappears in one week after contraceptive therapy is discontinued (12) suggests that the effect of these steroids on platelets is not metabolic. However, these same workers (12)
MARCH
1974
VOL. 9 NO. 3
297
CONTRACEPTION
298
MARCH 1974 VOL. 9 NO. 3
CONTRACEPTION TABLE
II
THE EFFECTS OF MESTRANOL/NORJZPHI?JDRW COMBINATION ON THE CURRJWI' INDUCED OCCLUSION TIMES IN RAT MESENTERY VESSELS Mean
100% Occlusion
Times
(Min)
Mestranol/Norethindrone Combination*
Control
46.1
(small rats)
23.2
(small rats)
50.9
(large rats)
26.4
(large rats)
* 100
g mestranol
+ 1 mg progestin
per 100 g rat.
Y-
MARCH
1974 VOL. 9 NO. 3
299
CONTRACEPTION
observed an increase in platelet electrophoretic mobility from women on oral contraceptives. Oral contraceptives have also been reported to increase platelet stickiness (11) I a result which could be "predicted" by our observations. The oral contraceptives could also exert a subtle but synergistic effect on the vascular system at least in so far as thromboembolic phenomena are concerned. Krane (26) has suggested that progesterone is a mild lathyrogen in rats. Chesney and coworkers (27) have shown that the enhanced adhesion of human platelets to lathyritic collagen is accompanied by ADP release and aggregation. If the contraceptive steroids act as mild lathyrogens in humans, then we would expect a larger number of platelets to adhere to vessel walls without being as strongly repulsed as in normal vessels. ACENOWLEDGEMENTS This work was supported in part by a grant (HL 15123) from the National Heart and Lung Institute, National Institute of Health, Bethesda, Maryland 20014. REFERENCES 1.
Vessey, M.P., and Doll, R. Investigation of relation between use of oral contraceptives and thromboembolic disease, A further report. Brit. Med. J., 2_, 651, (1969).
2.
Sartwell, P.E., Masi, A.T., Arthes, F.G., Greene, G.R. and Smith, H.E. Thrcmboembolism and oral contraceptives: An epidemiological case control study, in Second Report on the Oral Contraceptives, Food and Drug Administration, Advisory Committee on Obstetrics and Gynecology, Appendix 2A, pp. 21-36, August 1, 1969.
3.
Oral contraception Group for the study of stroke. increased risk of cerebral ischemia or thrombosis. New England J. Med., 288, 871 (1973).
4.
Cardiovascular Walters, W.A.W., and Lim, Y.L. in women receiving oral contraceptive therapy. 879 (1969).
300
MARCH
1974
and
dynamics Lancet
VOL. 9 NO. 3
CONTRACEPTION
5.
Haemodynamic changes Walters, W.A.W., and Lim, Y.L. in women taking oral contraceptives. J. Ob. and Gyn., (Brit.) 77, 1007 (1970).
6.
Fisch, I.R., Freedman, S.H., and Myatt, A.V. contraceptives, pregnancy and blood pressure. Amer. Med. Assn., 222, 1507 (1972).
7.
Plasma proteins and oral contraceptives. article. Lancet, 72 (1970).
8.
The effects of oral estrogen-progestin Hodges, R.M. compounds on blood coagulation factors. Int'l. J. Fertility, 13, 349 (1968).
9.
Shaper, A.G., and Kear, J. Estrogen, and platelets. Lancet, 569 (1968).
oral J.
Leading
progesterone
10.
Priest, C.M., and Thomson, Poller, L., aggregation during oral contraception. 4, 273 (1969).
11.
Adams, J.H., Mitchell, J.R.A., and Soppitt, G.D. Effects of oral contraceptives on lipoprotein lipase activity and platelet stickiness. Lancet, 333 (1970).
12.
Bolton, C.H., Hampton, J.R., and Mitchell, J.R.A. Effect of oral contraceptive agents on platelets and plasma - phospholipids. Lancet, 1336 (1968).
13.
Solash, J., Srinivasan, S., Jones, J.R., and Sawyer, The effects of oral contraceptives on the surP.N. face charge characteristics of the vascular system. Presented at the 11th Annual Conference on Hemostasis, N.Y.U. Medical Center, N.Y.C., February 3, 1973.
14.
Redner, A., Moser, C., Groshen, S., Ahrens, E., Lucas, T.R., Puvan, S.I., Srinivasan, S., and Sawyer, P.N. (Unpublished data).
15.
Sawyer, P.N., and Srinivasan, S. The role of electrochemical surface properties in thrombosis at vascular interfaces: Cumulative experience of studies in animals and man. Bull. N.Y. Acad. Med., Second Series, 48, 235 (1972).
UARCH
1974
VOL. 9 NO. 3
J.M. Platelet Brit. Med. J.,
30 I
CONTRACEPTION
16.
Srinivasan, S., and Sawyer, P.N. Ionic processes in and across blood vessel walls: Diffusion Processes in biological membranes: A.V. Chadwick, W.M. Muir, J.N. Sherwood, and F.L. Swinton, Editors, Proc. of the Graham Mem. Symp. Univ. of Strathclyde, Glasgow, Scotland, Gordon and Breach, 8.4:765,(1969).
17.
Costello, M., Stanczewski, B., Vriesman, P., Lucas, Correlations T.R., Srinivasan, S., and Sawyer, P.N. between electrochemical and antithrombogenic characteristics of polyelectrolyte materials. Trans. Amer. Sot. Artif. Int. Organs, 15, 1 (1970).
18.
Srinivasan, S., and Sawyer, P.N. Role of surface charge on the blood vessel wall, blood cells, and prosthetic materials in intravascular thrombosis. J. toll. Int. Sci., 32, 456 (1970).
19.
Chopra, P.S., Srinivasan, S., Lucas, T.R., and Sawyer, P.N. Effects of heparin, protamine, and low molecular weight dextran (m) on electrokinetic characteristics of canine blood vessel intima in vivo. Bull. N.Y. Acad. Med., Second Series, 43, 1206 (1967).
20.
SriniVaSan, S., Burrowes, C-B., Effects S.B., and Sawyer, P.N. lyte concentration on -in vitro across canine aorta and carotid Mat. Res., 1, 355 (1967).
21.
Intravascular thrombosis Sawyer, P.N., and Pate, J.W. of electric origin, U.S. Armed Forces Med. J., 4, 23 (1953).
22.
Bio-electric phenomena Sawyer, P.N., and Pate, J.W. as etiological agents in intravascular thrombosis. Surgery, 34, 491 (1953).
23.
Sawyer, P.N., and Srinivasan, S. Studies on the biophysics of intravascular thrombosis. Amer. J. Surgery 113, 42 (1967).
24.
Harshaw, D.H., and Sawyer, P.N. Electroosmotic characters of mammalian aorta and vena cava, .in Biophysical Mechanisms in Vascular Homeostasis and
302
LUCaS, T.R., Bauer, of varying electrostreaming potentials arteries. J. Biomed.
MARCH 1974 VOL. 9 NO. 3
CONTRACEPTION
Intravascular Thrombosis Appleton Century Crofts,
(Sawyer, P.N., Editor), New York (1965), p. 61-68.
25.
Sawyer, P.N., and Srinivasan, S. Electrokinetic characteristics of normal and atherosclerotic human aortae. Surgery, 63, 822 (1968).
26.
in Metabolic Effects of Gonadal Hormones Krane, S. and Contraceptive Steroids (Salhanick, H.A., Kipnis, D.M., and Vonde Weile, R.L., Editors), Plenum Press, New York, (1969), p. 534.
27.
Critical Chesney, C. MCI, Harper, E., and Coleman, R.W. role of the carbohydrate side chains of collagen in platelet aggregation. J. Clin. Invest., 51, 2693 (1972).
MARCH
1974 VOL. 9 NO. 3
*
Present address: Colorado 80302
+
Present address: Department of Obstetrics and Gynecology, University Of Malaysia, Kuala Lumpar, Malaysia
I.B.M.,
P.O. Box 1900, Boulder,
++ Department of Obstetrics and Gynecology, SUNY, Downstate Medical Center, Brooklyn, New York 11203 Accepted
for
publication
MARCH
1974
VOL.
January
9 NO. 3
15,
1974
291
CONTRACEPTION
INTRODUCTION Recent epidemiological studies (l-3) have indicated that women who use oral contraceptive steroids develop a higher incidence of thromboembolic disease than women who do not use them. Many recent studies have linked the use of the oral contraceptive drugs with abnormalities in cardiovascular function (4-6), plasma protein and blood coagulation factor levels (7,8), and platelet behavior (9-12). According to our work, it is very probable that oral contraceptives alter the charge characteristics of the vascular system. Work from this laboratory (13,14) indicates that alteration in the charge characteristics at the vascular interface may be linked to the thromboembolic phenomena observed in users of oral contraceptives (l-3). The characteristic surface potential of the vascular interface or blood cells may be measured by use of electrokinetic techniques. From our previous studies (15-20), it follows that: (a) under normal conditions, blood vessel intima and blood cell membranes are homogeneously negatively charged and demonstrate a negative zeta potential across blood vessel wall or cell surface-solution interface (15-20); (b) injury to blood vessels reduces the magnitude of the zeta potential (21,22); and (c) antithrombotic drugs increase the magnitude of the zeta potential while procoagulants decrease it (15-20). The techniques which we have been employing include measurement of the electrophoretic mobility of blood cells (18), streaming potential (15,16,18), and electroosmotic (15,16) measurements on blood vessels. The electrophoretic mobility of a particle or blood cell is directly proportional to its zeta potential; from the results of electroosmosis and streaming potential measurements, the zeta potential can be calculated easily. In the present investigation, we tried to determine the effects of an oral contraceptive preparation as well as of its constituent hormones on: (a) the electrophoretic' mobility of platelets; (b) the zeta potentials across blood vessel-solution interfaces as measured by electroosmosis; and (c) correlation of these in vitro surface charge effects with their action on an intact, in vivo For the latter study, the current clotting system. induced occlusion time in rat mesentery vessels was used
292
MARCH
1974 VOL. 9 NO. 3
CONTRACEPTION
as a measure steroids.
of the coagulant
METHODS
effect
of the contraceptive
AND MATERIALS
Electrophoresis Human platelets were obtained from female donors who Blood was drawn into were not taking oral contraceptives. glass tubes, containing l/10 volume of 3.2% sodium citrate solution, and centrifuged at 100 x g for 12 minutes. The supernatant plasma (platelet rich plasma) was diluted with Krebs (Ca++ free) solution (20) (1.5:5) containing varying amounts of the contraceptive steroids and incubated at 25-C for 1 hour in siliconized glass tubes before electrophorePlatelets were also tic mobility measurements were made. obtained from women who were taking a mestranol/norethindrone combination pill. All electrophoretic mobility measurements were performed using a Seaman micro-electrophoresis cell* at 37-C. The cell and platinized/platinum electrodes were thoroughly cleaned in a cont. sulfuric acid/cone. nitric acid (90/10) mixture and rinsed very well with triple distilled water, saturated sodium bicarbonate, and finally with triple distilled water. The plati?ized/platinum electrodes had a geometric area of 7.5 cm . Platelet movement was timed using a stopwatch and the eyepiece graticule. The average transit time of human platelets in one direction was approximately 11-12 sec. and at least 10 platelets were observed (5 in each direction) for each run. Electroosmosis Electroosmotic measurements were performed on sections of canine aorta which were removed from normal healthy dogs. The facia was removed from the advential side of the vessel and the aorta was then clamped between
* Micro-electrophoresis apparatus Bottisham, canibridge, England.
MARCH
1974 VOL. 9 NO. 3
obtained
from Rank Bros.,
293
CONTRACEPTION
each half cell (Figure 1). The cell was carefully filled with Izrebs solution which contained varying quantities of estrogen or progestin. The cell was then fitted with two silver/silver chloride electrodes: care was taken to exThe initial and clude all air bubbles from the system. final volume measurements were recorded from the manometers before and after a current of 1OmA was passed for The current was reversed and the volume three minutes. measurements recorded again after a period of three minThis procedure was repeated twice more (each elecutes. trode cathodic three times). This technique has been fully described elsewhere (23-25). Current
induced
occlusion
times
in rat mesenteric
vessels
Female Wistar rats weighing between 130 grams (small rats) and 225-275 grams (large rats) received an IP injection of a combination of mestranol/norethindrone daily for lo-12 days. All injections of contraceptives were made in the morning and on the afternoon of the last injection, the current induced occlusion time was measured. The rat was anesthetized with pentothal (IP injection), a midline incision was made and the mesoappendix extracted. The extracted portion of the mesoappendix was observed microscopically while a current of lO)(A was passed across the tissue by means of a suitable power supply and two microelectrodes. The extracted tissues of the mesoappendix were bathed in physiologic saline (37'C) to prevent necrosis and shock. Materials The mestranol and norethindrone used in this study were graciously supplied by Ortho Pharmaceutical Company. Pentothal sodium was obtained from Abbott Laboratories. RESULTS In Figure 2, the results of the effects of oral contraceptives on the electrophoretic mobility of platelets, which were incubated for one hour in Krebs (Ca++ free) solution containing varying quantities of oral contraceptives, are presented. Under these conditions, the changes in electrophoretic mobility are small and not highly significant (PeO.1). However, platelets which were obtained from women who had been taking oral contra-
294
MARCH
1974
VOL.
9 NO. 3
CONTRACEPTION Anode
Figure
MARCH
1:
Schematic
Cathode
of electroosmosis
1974 VOL. 9 NO. 3
apparatus.
295
CONTRACEPTION
Figure 2:
296
Results of platelet electrophoretic mobility studies. Krebs solution containing mestranol, norethindrone and a combination of mestranol and norethindrone were allowed to incubate with platelet rich plasma for 1 hour prior to measurement. Electrophoretic mobility of platelets obtained from women taking a mestranol/norethindrone "pill" is also shown.
MARCH
1974 VOL. 9 NO. 3
CONTRACEPTION
ceptives for at least 6 months, showed much in electrophoretic mobility (Figure 2).
larger changes
In Table I, the values for the zeta potentials across the blood vessel wall-Krebs solution (containing contraceptives) interface are compared to control values (Krebs solution without contraceptives). A test of the coagulant (pro or anti) ability of these compounds, in The effects of the oral contra%pwas necessary. a, tive steroids on the current induced occlusion times of The electrophoretic rat mesentery vessels were measured. mobility data and the electroosmosis data indicate that oral contraceptives may act as mild procoagulants -in vitro. The results of the current induced occlusion times in rat mesoappendix vessels (Table II) shows that in this system, the contraceptive steroids exert a strong procoagulant action. DISCUSSION The -in vitro electrokinetic experiments reveal that contraceptive steroids increase the magnitude of the zeta potential of both human platelets and canine blood vessel A strong procoagulant effect of these compounds walls. was exhibited -in vivo in the rat mesentery system. By extrapolation of the data obtained in non-human systems, one can tentatively conclude that the oral contraceptive steroids decrease the magnitude of the zeta potential of the elements of the vascular tree and, therefore, exert a procoagulant effect on the human vascular system by lowering the natural repulsive force between platelets and vessel walls. The oral contraceptives probably exert this procoagulant effect by their adsorption from blood on the surface of vessel walls and platelets with a consequent lowering of the zeta potential. The precise mechanism of the effect on the zeta potential by the contraceptives remains unknown. This could be a result of simple adsorption on the vascular elements or could result from some subtle metabolic change caused after adsorption on the vascular tree. The fact that platelet sensitivity toward ADP, exhibited by women on oral contraceptives, disappears in one week after contraceptive therapy is discontinued (12) suggests that the effect of these steroids on platelets is not metabolic. However, these same workers (12)
MARCH
1974
VOL. 9 NO. 3
297
CONTRACEPTION
298
MARCH 1974 VOL. 9 NO. 3
CONTRACEPTION TABLE
II
THE EFFECTS OF MESTRANOL/NORJZPHI?JDRW COMBINATION ON THE CURRJWI' INDUCED OCCLUSION TIMES IN RAT MESENTERY VESSELS Mean
100% Occlusion
Times
(Min)
Mestranol/Norethindrone Combination*
Control
46.1
(small rats)
23.2
(small rats)
50.9
(large rats)
26.4
(large rats)
* 100
g mestranol
+ 1 mg progestin
per 100 g rat.
Y-
MARCH
1974 VOL. 9 NO. 3
299
CONTRACEPTION
observed an increase in platelet electrophoretic mobility from women on oral contraceptives. Oral contraceptives have also been reported to increase platelet stickiness (11) I a result which could be "predicted" by our observations. The oral contraceptives could also exert a subtle but synergistic effect on the vascular system at least in so far as thromboembolic phenomena are concerned. Krane (26) has suggested that progesterone is a mild lathyrogen in rats. Chesney and coworkers (27) have shown that the enhanced adhesion of human platelets to lathyritic collagen is accompanied by ADP release and aggregation. If the contraceptive steroids act as mild lathyrogens in humans, then we would expect a larger number of platelets to adhere to vessel walls without being as strongly repulsed as in normal vessels. ACENOWLEDGEMENTS This work was supported in part by a grant (HL 15123) from the National Heart and Lung Institute, National Institute of Health, Bethesda, Maryland 20014. REFERENCES 1.
Vessey, M.P., and Doll, R. Investigation of relation between use of oral contraceptives and thromboembolic disease, A further report. Brit. Med. J., 2_, 651, (1969).
2.
Sartwell, P.E., Masi, A.T., Arthes, F.G., Greene, G.R. and Smith, H.E. Thrcmboembolism and oral contraceptives: An epidemiological case control study, in Second Report on the Oral Contraceptives, Food and Drug Administration, Advisory Committee on Obstetrics and Gynecology, Appendix 2A, pp. 21-36, August 1, 1969.
3.
Oral contraception Group for the study of stroke. increased risk of cerebral ischemia or thrombosis. New England J. Med., 288, 871 (1973).
4.
Cardiovascular Walters, W.A.W., and Lim, Y.L. in women receiving oral contraceptive therapy. 879 (1969).
300
MARCH
1974
and
dynamics Lancet
VOL. 9 NO. 3
CONTRACEPTION
5.
Haemodynamic changes Walters, W.A.W., and Lim, Y.L. in women taking oral contraceptives. J. Ob. and Gyn., (Brit.) 77, 1007 (1970).
6.
Fisch, I.R., Freedman, S.H., and Myatt, A.V. contraceptives, pregnancy and blood pressure. Amer. Med. Assn., 222, 1507 (1972).
7.
Plasma proteins and oral contraceptives. article. Lancet, 72 (1970).
8.
The effects of oral estrogen-progestin Hodges, R.M. compounds on blood coagulation factors. Int'l. J. Fertility, 13, 349 (1968).
9.
Shaper, A.G., and Kear, J. Estrogen, and platelets. Lancet, 569 (1968).
oral J.
Leading
progesterone
10.
Priest, C.M., and Thomson, Poller, L., aggregation during oral contraception. 4, 273 (1969).
11.
Adams, J.H., Mitchell, J.R.A., and Soppitt, G.D. Effects of oral contraceptives on lipoprotein lipase activity and platelet stickiness. Lancet, 333 (1970).
12.
Bolton, C.H., Hampton, J.R., and Mitchell, J.R.A. Effect of oral contraceptive agents on platelets and plasma - phospholipids. Lancet, 1336 (1968).
13.
Solash, J., Srinivasan, S., Jones, J.R., and Sawyer, The effects of oral contraceptives on the surP.N. face charge characteristics of the vascular system. Presented at the 11th Annual Conference on Hemostasis, N.Y.U. Medical Center, N.Y.C., February 3, 1973.
14.
Redner, A., Moser, C., Groshen, S., Ahrens, E., Lucas, T.R., Puvan, S.I., Srinivasan, S., and Sawyer, P.N. (Unpublished data).
15.
Sawyer, P.N., and Srinivasan, S. The role of electrochemical surface properties in thrombosis at vascular interfaces: Cumulative experience of studies in animals and man. Bull. N.Y. Acad. Med., Second Series, 48, 235 (1972).
UARCH
1974
VOL. 9 NO. 3
J.M. Platelet Brit. Med. J.,
30 I
CONTRACEPTION
16.
Srinivasan, S., and Sawyer, P.N. Ionic processes in and across blood vessel walls: Diffusion Processes in biological membranes: A.V. Chadwick, W.M. Muir, J.N. Sherwood, and F.L. Swinton, Editors, Proc. of the Graham Mem. Symp. Univ. of Strathclyde, Glasgow, Scotland, Gordon and Breach, 8.4:765,(1969).
17.
Costello, M., Stanczewski, B., Vriesman, P., Lucas, Correlations T.R., Srinivasan, S., and Sawyer, P.N. between electrochemical and antithrombogenic characteristics of polyelectrolyte materials. Trans. Amer. Sot. Artif. Int. Organs, 15, 1 (1970).
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Srinivasan, S., and Sawyer, P.N. Role of surface charge on the blood vessel wall, blood cells, and prosthetic materials in intravascular thrombosis. J. toll. Int. Sci., 32, 456 (1970).
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Chopra, P.S., Srinivasan, S., Lucas, T.R., and Sawyer, P.N. Effects of heparin, protamine, and low molecular weight dextran (m) on electrokinetic characteristics of canine blood vessel intima in vivo. Bull. N.Y. Acad. Med., Second Series, 43, 1206 (1967).
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SriniVaSan, S., Burrowes, C-B., Effects S.B., and Sawyer, P.N. lyte concentration on -in vitro across canine aorta and carotid Mat. Res., 1, 355 (1967).
21.
Intravascular thrombosis Sawyer, P.N., and Pate, J.W. of electric origin, U.S. Armed Forces Med. J., 4, 23 (1953).
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Sawyer, P.N., and Srinivasan, S. Studies on the biophysics of intravascular thrombosis. Amer. J. Surgery 113, 42 (1967).
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Harshaw, D.H., and Sawyer, P.N. Electroosmotic characters of mammalian aorta and vena cava, .in Biophysical Mechanisms in Vascular Homeostasis and
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Intravascular Thrombosis Appleton Century Crofts,
(Sawyer, P.N., Editor), New York (1965), p. 61-68.
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Sawyer, P.N., and Srinivasan, S. Electrokinetic characteristics of normal and atherosclerotic human aortae. Surgery, 63, 822 (1968).
26.
in Metabolic Effects of Gonadal Hormones Krane, S. and Contraceptive Steroids (Salhanick, H.A., Kipnis, D.M., and Vonde Weile, R.L., Editors), Plenum Press, New York, (1969), p. 534.
27.
Critical Chesney, C. MCI, Harper, E., and Coleman, R.W. role of the carbohydrate side chains of collagen in platelet aggregation. J. Clin. Invest., 51, 2693 (1972).
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1974 VOL. 9 NO. 3