1) One case of primary aldosteronism was reported. Adenoma of the left adrenal was confirmed on operation.
2) In incubation experiments, overproduction of aldosterone and corticosterone was noted in the adenomatous tissue while cortisol and cortisone were produced only small amounts.
3) The non-adenomatous tissue of the removed adrenal produced aldosterone about 1/3 the adenomatous tissue, although it produced more than normal adrenal tissue. The production of corticosterone, however, was very low.
4) When corticosterone-4-C14 was added to an incubation medium with slices of adenoma, biosynthetic conversion of the radioactive steroid to aldosterone was greatly enhanced, 5 times as much as in the non-adenomatous tissue. Thus, an autonomous increase of the activity of 18-hydroxylase is reasonably considered.
5) Histologically, hyperplasia was found in zona glomerulosa of the nonadenomatous portion of the removed adrenal cortex, suggesting some stimulating factor which continuously promotes a secretion of aldosterone. The pathogenesis of primary aldosteronism was discussed from a viewpoint of a renal stimulating factor.