Reduced responsiveness of glomerulosa cells after prolonged stimulation with angiotensin II.

The purpose of this study was to examine whether sustained exposition to angiotensin modifies the responsiveness of adrenal glomerulosa cells when extra-adrenal factors are eliminated. Isolated rat glomerulosa cells were stimulated for 6 h in a superfusion system with angiotensin II or potassium. Their responsiveness to angiotensin II, potassium, and corticotropin (ACTH) was examined before and after the superfusion. Stimulation of the cells during the superfusion with angiotensin II or with potassium reduced their responsiveness to all three stimuli. The steroid synthesis inhibitor aminoglutethimide, applied during the superfusion, overcame the effect of potassium but failed to influence that of angiotensin. This suggests that the reduced responsiveness after stimulation with potassium is related to the increased steroid production whereas the action of angiotensin is independent of that. The results establish the existence of desensitization to angiotensin in the absence of modifying extra-adrenal factors.