Decreases in renin and aldosterone secretion in alloxan diabetes: an effect of insulin deficiency.

The effect in the rat of alloxan diabetes (with and without insulin treatment) on renin and aldosterone secretion was examined. Rats with diabetes for 7 weeks were found to have lower PRA than nondiabetic controls. The decrease in PRA appeared to result from insulin deficiency since PRA was normal in diabetic rats given insulin. In a second set of animals, which were killed after 3 weeks, in vitro measurements of aldosterone production by perifused adrenal capsular tissue were carried out. Production of aldosterone was greatest by adrenal capsular tissue from insulin-treated diabetic rats where both basal and potassium-stimulated aldosterone production were higher than diabetic rats not given insulin. Although the reduced aldosterone production associated with untreated diabetes may have been a result of reduced in vivo exposure of adrenal tissue to angiotensin II, a chronic adrenotrophic influence of insulin could not be ruled out. In summary, insulin appears to be necessary for normal renin and aldosterone secretion in the diabetic rat.