NADPH diaphorase histochemistry in the adrenal gland of the mouse.

NADPH diaphorase, an enzymatic activity which, in neuronal tissue, is considered to be identical to nitric oxide synthase was localized in ganglion cells and nerve fibers of the mouse adrenal medulla. Staining was inhibited by treatment with N-ethylmaleimide, but was not influenced by removal of Ca++ or the presence of specific inhibitors of nitric oxide synthase. Reaction with NADH as the electron donor resulted in uniform staining of the adrenal medulla. These results suggest that nitric oxide is synthesized in intrinsic neurons and extrinsic axons of the mouse adrenal medulla and support the idea that adrenal function is influenced by nitric oxide.