Local inhibition of nitric oxide temporarily stimulates aldosterone secretion in conscious sheep in vivo

The effect of localized blockage of endogenous nitric oxide (NO) on basal a ldosterone secretion was studied in conscious sheep with autotransplanted a drenal glands. We have shown that infusion of the NO synthase (NOS) inhibit or N-G-nitro-L-arginine methyl ester (L-NAME; 130 mug/l blood flow) signifi cantly stimulated basal aldosterone secretion rate (ASR). This stimulatory effect was seen up to 4 h of infusion. Beyond this time point, however, the elevated ASR level was not sustained, and it was seen to drop markedly to lower than control values at 5 h. L-NAME had no effect on cortisol secretio n rate (FSR) during the first 4 h of infusion, but a significant reduction in FSR was seen by the 8-h time point. Adrenal blood flow was consistently decreased in association with long L-NAME infusion. Additionally, L-NAME wa s shown to have no effect on aldosterone secretion when infused systemicall y. We conclude that the relationship between NO and aldosterone secretion i s an inhibitory one, in which NO seems to have a negative effect on basal a ldosterone secretion.