Effect of Adrenalectomy and Glucocorticoids on the Secretion and Absorption of Hydrogen Ion

Vol. 50, No.6 Printed in U.S.A.

GASTROENTEROLOGY

Copyright © 1966 by The Williams & Wilkins Co.

EFFECT OF ADRENALECTOMY AND GLUCOCORTICOIDS ON THE SECRETION AND ABSORPTION OF HYDROGEN ION ALLAN R. COOKE, M.R.A.C.P., ROY M. PRESHAW, F.R.C.S. (ED.), and MORTON L GROSSMAN, M.D., PH.D. Research, Veterans Administration Center, Los Angeles, California, and Department of Physiology, UCLA Center for the Health Sciences, Los Angeles, California

Normal gastric mucosa offers a strong barrier to the movement of various cations, including hydrogen ion, from lumen to blood. 1 The mechanism for maintaining this barrier is unknown. We here report a study, of dogs with Heidenhain pouches, designed to determine whether adrenal cortical function influences this barrier. Previous studies2 of the effect of adrenalectomy and corticosteroid replacement have been concerned only with the secretion of hydrogen ion; the present study deals both with absorption and secretion of hydrogen ion.

Methods Seven adult mongrel dogs weighing 14 to 18 kg were used. Under sodium pentobarbital anesthesia, a vagally denervated pouch of the oxyntic gland area (Heidenhain type) was constructed and a Gregory cannulas was inserted. The dogs were allowed to recover fully and tests were started not sooner than 4 weeks following operation. The animals were fasted for 18 hr prior to each test. Studies were made during four periods: Received December 15, 1965. Accepted January 11, 1966.

Address requests for reprints to: Dr. Morton

I. Grossman, Veterans Administration Center,

Los Angeles, California 90073. This work was supported in part by Grant 08354 from the United States Public Health Service. We gratefully acknowledge the technical assistance of Gerald Messick. Allan R. Cooke is a Travelling Fellow, Postgraduate Committee of Medicine, Sydney, Australia. Roy M. Preshaw was a Harkness Fellow of the Commonwealth Fund. His present address is: McGill University, Montreal, Canada.

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1. Control studies in the animals before adrenalectomy. 2. Studies following bilateral adrenalectomy while the animals were fed a liberal salt diet (about 4 g of NaCl per day) and given deoxycorticosterone acetate (DOCA), 2.5 mg intramuscularly every 2nd day. Tests were started 1 month after adrenalectomy, at which time the animals were in good health. 3. Studies following bilateral adrenalectomy while on DOCA and hydrocortisone, 25 mg intramuscularly every 2nd day. 4. Studies following bilateral adrenalectomy while on no therapy apart from salt added to the food or parenteral saline. During each of the four periods, two types of tests were carried out, one to measure absorption of acid from the Heidenhain pouch under basal conditions, the other secretion of acid following histamine stimulation. Absorption of acid was measured by instilling 25 ml of 0.15 N HCl into the pouch via a vertical glass reservoir attached to the metal cannula of the pouch by a rubber tube, similar to the method of Burstall and Schofield: During the observation period the contents of the pouch were mixed by the frequent spontaneous contractions. At the end of each 30-min period the contents were allowed to drain completely. Four successive 30-min observations were made for each experiment. The volume of the contents was measured to 0.1 ml and the concentration of acid determined by titration of a I-ml sample against 0.2 N N aOH to pH 7 in automatic titrator (Autoburet, Radiometer, Copenhagen). The absorption of acid in micro equivalents per 30 min was calculated by subtracting the amount of acid recovered from the pouch from the amount of acid instilled into the pouch. The secretory capacity of the pouch was studied by stimulation with a continuous intravenous infusion (30 ml/hr) of histamine dihydrochloride dissolved in 0.15 M NaCl in varying concentrations to give the desired dosage. The juice was collected every 15 min by gravity

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COOKE ET AL.

drainage. The volume of each sample was measured and the concentration of acid determined by titration of a O.2-ml sample with 0.2 N NaOH to pH 7. In a number of experiments, blood was taken and the plasma osmolality was measured (Osmometer, Advanced Instruments, Newton, Mass.) . For each dog the significance of differences between various phases of treatment was determined by the U test of Mann and Whitney" The probabilities derived from the tests in individual dogs were combined by the method of Fisher."

Results

Secretory Studies Acid response to histamine in adrenalectomized dogs. All of seven dogs showed a significant decrease in acid output at all doses of histamine following adrenalectomy (fig. 1). At the highest dose (6.0 mg/hr) collapse occurred in all adrenalectomized dogs (DOCA maintained). The collapse consisted of the animal being unable to stand, marked hyperventilation, and usually incontinence of urine and feces. Loss of consciousness did not occur unless the histamine infusion was continued. When the histamine infusion was stopped recov1200 c

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Vol. 50, No.6

ery followed within 5 mIll; intravenous hydrocortisone was not required. The reduction in acid output was due to a decrease in volume rate of secretion and not to a decrease in hydrogen ion concentration. The relationship between volume rate and hydrogen ion concentration was unchanged by adrenalectomy (fig. 2). Effect of hydrocortisone on adrenalectomized dogs. Five adrenalectomized animals maintained on DOCA were given 100 mg of hydrocortisone intravenously while being stimulated with a submaximal dose of histamine (1.5 mg/ hr). No increase in acid output occurred within 3 hr of giving hydrocortisone. At the end of this test 25 mg of hydrocortisone were given intramuscularly and this schedule was continued every 2nd day. Within 24 hr maximal acid output in response to histamine had returned to preadrenalectomy control levels in all five animals. By the 5th and 8th days (fig. 3) secretory responses to histamine were greater than control. Basal secretion was also greater during the 5th and 8th days but not statistically significant (P > 0.05). The increase in acid output was associated with an increase both in volume and in hydrogen ion concentration (fig. 2). Hydrogen ion concentration rose to values as high as 172 mEq/ liter (fig. 4). In individual dogs, the maximal hydrogen ion concentration during the preadrenalectomy control ranged from 156 to 162 mEq/ liter; during the 5th to 8th days of hydrocortisone administration the maximal hydrogen ion concentration ranged from 166 to 172. This effect was not associated with a change in plasma osmolality, as this was found to be in the normal range (287 to 300 milliosmoles/ kg of water) and never higher than gastric juice. Studies on the 27th day showed that hydrogen ion concentration and acid output had returned to preadrenalectomy control levels (fig. 3). None of the animals receiving hydrocortisone collapsed with the highest dose of histamine (6.0 mg/ hr). Acid response in adrenalectomized animals receiving saline alone. The animals were re-studied approximately 3 weeks after discontinuing all therapy apart from daily subcutaneous infusion of 0.15 M saline

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SECRETION AND ABSORPTION OF HYDROGEN IONS

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(500 ml). Gastric pouch acid output was markedly reduced when compared to preadrenalectomy control responses but not significantly different from the response obtained when the animals were maintained on salt and DOCA (fig. 5). All animals collapsed with the highest dose of histamine. The decrease in acid output was due to a decrease in volume rate of secretion and not to a fall in hydrogen ion concentration (fig. 2). In figure 6 it is seen that despite the varying maximal acid output during the different treatment phases after adrenalectomy, the maximal hydrogen ion concentration was relatively constant except during hydrocortisone administration when a peak value of 171 mEq/ liter was obtained. Only in the terminal phases of the period when the animal was receiving no therapy did the hydrogen ion concentration fall.

Absorption Studies Under basal conditions about 100 p.Eq of hydrogen ion were absorbed from the pouch every 30 min following the instillation of 25 ml of 0.15 N HCI (fig. 7). After adrenalectomy, whether the animals were receiving DOCA, DOCA + hydrocortisone, or saline alone, the amount of acid absorbed from the pouch was not significantly changed (P > 0.1 all phases). Discussion

Although bilateral adrenalectomy has been shown in acute experiments to reduce gastric secretion markedly in the raF-ll and cat,12 very little work has been done in chronic preparations. In chronic gastric fistula rats Bralow et aP3 found that bilateral adrenalectomy reduced spontaneous gastric acid secretion. In dogs, Sigel et al.,14

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COOKE ET AL.

Vol. 50, No.6

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FIG. 5. Dose-response curves to histamine dihydrochloride before and after adrenalectomy (saline alone and DOCA plus saline maintenance). E ach line is the mean of six experiments in two dogs.

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SECRETION AND ABSORPTION OF HYDROGEN IONS

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using a single dose of histamine diphosphate (0.5 mg subcutaneously), found gastric secretion from pouches was decreased following adrenalectomy. Wiederanders et aU 5 and Nicoloff et aU6 studied the effect of cortisone replacement on the 24-hr gastric secretion of Heidenhain pouch dogs following bilateral adrenalectomy but made no studies when the animals were not receiving glucocorticoids. We have found that bilateral adrenalectomy profoundly reduced the gastric secretory response to a wide range of histamine doses. The mean maximal response after

adrenalectomy was 41% of that found in the intact animal. At high histamine dosage (6.0 mgjhr) all adrenalectomized animals collapsed. This occurred in animals maintained on DOCA plus saline or saline alone but not in those receiving glucocorticoids. The collapse was not in the nature of an acute adrenal insufficiency crisis since no therapy apart from stopping the histamine infusion was required. It is possible that this collapse was vascular in type since it has been shown that adrenalectomized animals fatigue sooner than normal dogs under stressful conditions,l7 and also that

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this fatigue is preceded by a falling blood pressure. IS Furthermore, adrenal cortical extracts have been shown to restore to normal the vascular unresponsiveness of adrenalectomized animals. 19 In our animals the protection afforded by glucocorticoids was probably on a vascular basis. As well as protecting the animals from the toxic effects of histamine, glucocorticoids restored gastric acid output to normal and later to supranormal levels. Secretion returned to control levels within 24 hr and was above control levels by the 5th day (figs. 3 and 4) . This delay in glucocorticoid action is difficult to explain on a vascular basis, since the vascular changes found in the mesoappendix of the adrenalectomized rat were quickly reversed. 19 The increase in acid output resulted from an increase both in volume rate of secretion as well as in hydrogen ion concentration (figs. 2 and 4). Both these increases were significant but transitory (figs. 3 and 6), acid output and hydrogen ion concentration returning to normal by the 27th day, despite continued administration of hydrocortisone. Acid output did not remain at levels higher than those obtained in preadrenalectomy controls as reported by Sigel et al.;14 however, he used a dose of 50 mg of cortisone per day, which is equivalent to approximately 4 times the dose we gave, and he reported that the effect was dose-related. Wiederanders15 could not increase gastric secretion above control levels in adrenalectomized dogs with doses of cortisone ranging from 10 mg/day to 300 mg/day. We are unable to explain the supranornal levels of hydrogen ion concentration obtained in our experiments. Various workers 7 , 8, 10 have found that glucocorticoids have restored gastric secretion to normal in pylorus-ligated rats, whereas others have found only partial restoration or no effect. 9 ,l1 Welbourne and Code 8 found that secretion returned to normal by the 3rd day, whereas we observed an effect within 24 hr. Davenport and Chavre,20 in an in vitro stomach removed from a normal or adrenalectomized mouse, could not demonstrate any effect on gastric scretion with glucocorticoids.

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Absorption of acid from the Heidenhain pouch following adrenalectomy was unaltered when compared to the intact animal (fig. 7). This indicates that the reduction of acid output following adrenalectomy was not caused by increased reabsorption of secreted acid. Davenport et aP have shown that the gastric mucosal barrier can be altered by eugenol so that large quantities of hydrogen ion escape across the mucosa into the blood, thus causing an apparent decrease in acid output in response to secretory stimulants. The evidence bearing on the mechanism of decrease of acid secretion following adrenalectomy has been reviewed by Crean;2 neither structural nor metabolic changes have been consistently shown. It would appear from our results that the mucosal barrier is not at fault. Summary

The effect of bilateral adrenalectomy on the secretion and absorption of acid in Heidenhain pouch dogs has been investigated. It was found that bilateral adrenalectomy significantly decreased the acid output to varying doses of histamine and did not alter the relation between hydrogen ion concentration and the volume rate of secretion. The absorption of acid by the gastric mucosa was not changed by adrenalectomy. Glucocorticoids but not mineralocorticoids restored secretion to normal levels. These experiments indicate that the impaired secretion of acid in response to histamine in adrenalectomized dogs is not attributable to increased leakage of secreted acid from lumen to blood. REFERENCES 1. Davenport, H. W., H. A. Warner, and C. F. Code. 1964. Functional significance of gastric

mucosal barrier to sodium. Gastroenterology 47: 142-152. 2. Crean, G. P. 1963. The endocrine system and the stomach. Vitamins Hormones (N. Y.) 21: 215-280. 3. Gregory, R. A. 1958. Gastric secretory responses after portal venous ligation. J. Physiol. (London) 144: 123-137. 4. Burstall, P. A., and B. Schofield. 1953. Secretory effects of psychic stimulation and insulin hypoglycemia on Heidenhain gastric

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5. 6.

7. 8.

9.

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11.

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pouches III dogs. J. Physiol. (London) 1~0: 383-408. Siegel, S. 1956. Non-parametric statistics for the behavioral sciences. McGraw-Hill Book Co., Inc., New York. Fisher, R. A. 1948. Statistical methods for research workers. Oliver and Boyd, Ltd., Edinburgh. T eurkischer, E., and E . Werthernier. 1945. Adrenalectomy and gastric secretion. J. Endocr. 4: 143-151. W elbourne, R B., and C. F. Code. 1953. Effects of cortisone and of adrenalectomy on secretion of gastric acid and on occurrence of gastric ulceration in the pylorusligated rat. Gastroenterology [133: 356-362. M adden, R J., and H. H. Rammsburg. 1951. Gastric secretion in the adrenalectomized rat . Endocrinology 49: 82-85. K yle, T., and R B. Welbourne. 1956. Influence of the adenohypophysis and the adrenal cortex on gastric secretion in the rat. Brit. J . Surg. 44: 241-247. Madden, R J., and H. H. Ramsburg. 1951. Adrenalectomy in the Shay rat . Gastroenterology 18: 128-134. D e Corral-Saleta, J . M. 1960. Infiuencia de las suprarrenales sobre la secreci6n gastrica. Rev. Esp. Fisiol. 15: 231-239. Bralow, S. P., S. A. Komarov, and H. Shay. 1964. Effect of total adrenalectomy on gastric secretion in chronic gastric fistula rats. Amer. J. Physiol. [1306: 1309-1314.

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14. Sigel, B., J . G. Bassett, and D . R. Cooper. 1956. The effect of cortisone on histamine

stimulation of gastric secretion in the adrenalectomized dog. Surg. F orum 7: 362365. 15. Wiederanders, R. E., K. L. Glassen, W. G. Gobbel, and M. M. Doyle. 1960. Effect of cortisone acetate on gastric secretion. Ann. Surg. 15[13 : 119-128. 16. Nicoloff, D. M., N. H. Stone, E. T. Peter, R. Doberneck, and O. H. Wangensteen. 1961. Effect of cortisone on gastric secretion in adrenalectomized dogs. J. A. M. A. 178: 1005-1007. 17. Ramey, E. R , M . S. Goldstein, and R Levine. 1950. Mechanism of muscular fatigue in adrenalectomized animals. Amer. J. Physiol. 16[13: 10-16. 18. Goldstein, M. S., E. R. Ramey, and R. Levine. 1950. Relation of muscular fatigue

in the adrenalectomized dog to inadequate circulatory adjustment. Amer. J . Physiol. 163: 561-565. 19. Fritz, 1., and R. Levine. 1951. Action of adrenal cortical steroids and norepinephrine on vascular responses of stress in adrenalectomized rats. Amer . J. Physiol. 165: 456-465. 20. D avenport, H. W ., and V. J . Chavre. 1950. The lack of effect of the adrenal hormones upon gastric acid secretion. Endocrinology 47: 193-197.