Effects of stimulation on the steroid profile formed by rat adrenal capsule tissue incubated in vitro

A characteristic of the response of non-dispersed rat adrenal capsule tissue (mainly zona glomerulosa) to ACTH stimulation is that corticosterone and aldosterone production is increased whereas 18-hydroxy-deoxycorticosterone (18-OH-DOC) is not. The effects of potential second messengers on the steroid profile were compared with those of ACTH and K+ ions in adrenal capsule incubations. ACTH stimulated corticosterone, 18-hydroxycorticosterone and aldosterone, but not 18-OH-DOC. In contrast, K+ (5.9 mM) stimulated 18-OH-DOC as well as the other capsule products. Compared with controls incubated with EDTA, the addition of Ca2+ and Mg2+ ions invariably stimulated aldosterone and 18-hydroxycorticosterone, while the effects on corticosterone were variable, and 18-OH-DOC production was unaltered. Addition of dibutyryl cyclic AMP (1 mM and 0.3 mM) or cyclic GMP (1mM) stimulated all products. The results show that Ca2+ ions and dibutyryl cAMP may have slightly different effects in that the cyclic nucleotides can stimulate all products whereas Ca2+ and Mg2+ ions preferentially support aldosterone and 18-hydroxycorticosterone. However, none of the potential intracellular stimulants studied fully reproduce the characteristic response of non-dispersed tissue to ACTH in which the secretion of corticosterone and 18-hydroxy-DOC is disassociated.