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SUMMARY
Organ cultures of extra-adrenal chromaffin cells obtained from 2-day-old rabbits were prepared in a medium composed of horse serum and Medium 199. Corticosterone, 10 μg./ml., was added to half the cultures; the remainder served as controls. After 6 days the explants were examined histochemically by light and electron microscopy or were homogenized and assayed for adrenaline and noradrenaline.
There was a marked increase in the concentration of adrenaline in the corticosterone-treated explants, accompanied by light and electron microscopic histochemical evidence for adrenaline storage. Mixtures of adrenaline- and noradrenaline-storing chromaffin granules were observed in the same chromaffin cell in corticosterone-treated specimens. The control cultures showed little change.
These findings are in keeping with the hypothesis that the local concentration of adrenocortical steroids is an important factor in determining whether chromaffin cells synthesize and store adrenaline or noradrenaline. At a concentration of corticosterone similar to that found in the adrenal venous sinuses of the normal rabbit substantial quantities of adrenaline appear in cells which normally almost entirely store noradrenaline.
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Search for other papers by R. E. COUPLAND in
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SUMMARY
Slices of adrenal glands of 4- to 6-months-old Sprague—Dawley rats were cultured for up to 6 days under air or hyperbaric oxygen in a mixture of 80% Parker's tissue culture Medium 199 and 20% horse serum. The use of hyperbaric oxygen instead of air resulted in a marked improvement in the microscopic appearance of the adrenal slices in cultures of 3–6 days duration.
There was a marked stimulation of steroid output in cultures exposed to hyperbaric oxygen during the first 24 hr. After this time, in spite of the improved histological appearance of the tissue slices, no significant difference in steroid output was observed.
Female glands secrete about twice as much steroid per unit weight as male glands under similar hyperbaric conditions.
Corticosterone, 18-hydroxydeoxycorticosterone and 18-hydroxycorticosterone were the most abundant steroids secreted, but smaller amounts of aldosterone and deoxycorticosterone were also identified. Hyperbaric oxygen did not materially affect the relative amounts of the various steroids.
The presence of a greater quantity of adrenocortical tissue in female animals was confirmed. The absolute weight of the medulla in male animals was significantly greater than that of females of the same age, but when expressed in terms of body weight the female medulla was greater than the male medulla.
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SUMMARY
Exposure of organ cultures of rat adrenal glands to hyperbaric oxygen at 2 atm. increases steroid output during the first 24 hr. but the secretion rate falls after that time. This reduction is partially prevented by the addition of progesterone and during the period 24–48 hr. completely prevented by the addition of progesterone together with glucose-6-phosphate, glucose-6-phosphate dehydrogenase and nicotinamide adenine dinucleotide phosphate.
Addition of bovine and synthetic adrenocorticotrophin to cultures maintained in hyperbaric oxygen results in a further increase in steroid secretion during the period 0–6 hr. Addition of metyrapone results in a reduction in the output of corticosterone, 18-hydroxycorticosterone and aldosterone.
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SUMMARY
When organ cultures of rat adrenal glands are exposed to gaseous phases of air and hyperbaric oxygen at 2 atm., Δ5-3β-hydroxysteroid dehydrogenase is inactivated in both gaseous phases. During the first 24 hr., inactivation is more rapid in air but after 24 hr. little or no difference in rate is observed and little or no activity remains after 72 hr.
Estimates of 11- and 18-steroid hydroxylases after various periods of culture in the two gaseous phases and in the absence of exogenous substrate showed similar rates of inactivation during the first 24 hr. When progesterone was used as an exogenous substrate more enzyme activity remained after 24 hr. culture in hyperbaric oxygen than in air. Little enzyme activity remained after 72 hr.
The activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconic dehydrogenase and iso-citric dehydrogenase fall markedly when organ cultures of rat adrenal glands are incubated for 24 hr. in air and in hyperbaric oxygen at 2 atm.
The enzymes were, however, no more sensitive to hyperbaric oxygen than to air.
