INFLUENCE OF SODIUM AND POTASSIUM DIETS ON ADRENAL VASOPRESSIN CONTENT AND DIRECT EFFECTS OF VASOPRESSIN ON ALDOSTERONE SYNTHESIS IN ADRENOCORTICAL-CELLS

Two questions were investigated to elucidate the adrenal function of a rginine vasopressin (AVP) in controlling aldosterone secretion: Are va sopressin tissue concentrations in the adrenal modulated by diets that influence aldosterone secretion? Does its direct stimulation of aldos terone secretion from adrenal cells in vitro suggest that vasopressin plays an important role in controlling aldosterone? Diets that modulat e aldosterone secretion from rat adrenals did not modulate concentrati ons of AVP in this tissue: Adrenal AVP concentrations did not differ s ignificantly between rats on low- and high-sodium (22.9 +/- 3.8 and 32 .4 +/- 6.4 pg/g) or between low- and high-potassium (25.6 +/- 2.5 and 12.5 +/- 7.3 pg/g) diets. Although the existence of AVP receptors on a drenocortical cells incubated in vitro and the stability of AVP during cell incubation was confirmed, AVP had only a minor direct effect on steroid secretion in short-term incubations alone and in combination w ith angiotensin II (A II), potassium and atrial natriuretic factor (AN F). The importance of AVP for an indirect control of aldosterone secre tion in vivo is discussed.