Study of Adrenocortical Function in Fever. Effect of high temperature on corticoidogenesis in isolated bovine adrenocortical cells / 日本温泉気候物理医学会雑誌

ABSTRACT

To study the adrenocortical function in fever, we examined the effect of high temperatures on the corticoidogenesis (CG) in isolated bovine adrenocortical cells. To evoke CG, a stimulus was given using adrenocorticotropic hormone (ACTH, 1pM to 10nM), which stimulates the receptor operated Ca²⁺ channel (ROC) and adenylate cyclase activity; dibutyryl cyclic AMP (db-cAMP, 1mM), which mimics intracellular action of cyclic AMP; and high (30mM) K⁺, which activates the voltage dependent Ca²⁺ channel (VDC). Cells were incubated for 1 hour with each of the above mentioned secretaogues at 37°C, 40°C, and 42°C (only for ACTH). Compared with incubation at 37°C, the log dose response curve of ACTH shifted to the right, the maximal effect decreased to about 60% at 40°C, and CG ceased at 42°C. The use of Ca²⁺ (1.2mM) alone evoked CG via the nonspecific Ca²⁺ channel (NSC) at 37°C, but not at 40°C. 30mM K⁺-induced CG decreased to below 50% at 40°C, but 1mM db-cAMP-induced CG decreased only to 80%. However, the conversion of 25-hydroxycholesterol to corticoid was not affected at 40°C<br>The results of these experiments show that VDC and NSC are not the main factors of CG at 40°C and that the enzyme activity beyond the side chain cleavage of cholesterol is not affected. Since the increases in cyclic AMP production and intracellular Ca²⁺ are essential in various stimulants-induced CGs, it is suggested that adenylate cyclase and ROC play a more important role in CG at 40°C than VDC and NSC.