Trophic effects of potassium loading on the rat zona glomerulosa: permissive role of ACTH and angiotensin II

Abstract

Abstract. The trophic effects of chronic potassium loading on the rat zona glomerulosa were investigated by morphometric and radioimmunological methods. Potassium loading exerted a potent adrenoglomerulotrophic effect in saline treated control rats, but it was not able to reverse the captopril- and dexamethasone-induced atrophy of the zona glomerulosa. However, if the captopril/dexamethasone administered rats were given maintenance doses of angiotensin II and ACTH, potassium loading was found to exert a strong trophic action. The hypothesis is advanced that potassium loading requires the integrity of both the renin-angiotensin system and the hypothalamo-hypophyseal axis to exert its powerful direct stimulating effect on the growth and steroidogenic capacity of the rat zona glomerulosa.