Adrenocortical Function during Hypothermia. (No.2). Inhibitory effect of low temperature on corticoidogenesis in isolated bovine adrenocortical cells.:Inhibitory effect of low temperature on corticoidogenesis in isolated bovine adrenocortical cells

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Effects of low temperature on corticoidogenesis (CG) were studied in isolated bovine adrenocortical cells. In the presence of Ca2+, cells were incubated with adrenocorticotropic hormone (ACTH) at 27°C and 37°C for 1 hour. After the incubation, the amount of corticoid was measured fluorometrically. After the incubation at 27°C, as compared with that at 37°C, the CGs induced by 10pM and 1nM ACTH decreased, but the CG induced by 10nM ACTH was not affected. Even in the absence of extracellular Ca2+, 10nM ACTH could induce the same degree of CGs at 37°C and 27°C, There was no difference in the amount of conversion of 25-hydroxycholesterol to corticoid between the incubations at 37°C and 27°C. The amount of conversion at 20°C, however, was significantly lower.Our study shows that Ca2+ is not an important second messenger for CG at 27°C, and that the enzyme activity beyond side chain cleavage of cholesterol (SCC) does not diminish.Because cyclic AMP and Ca2+ are known as second messengers of ACTH, it is suggested that cyclic AMP plays a more important role than Ca2+ in CG during hypothermia and that ACTH not only stimulates SCC but also activates enzyme (s) beyond SCC to evoke CG in the case of deep hypothermia.
一般社団法人日本温泉気候物理医学会の論文