Monkey isolated mesenteric arterial rings denuded of endothelium constricted upon transmural nerve stimulation (TNS) in the absence of active muscle tone. The constriction was potentiated by N omega-nitro-L-arginine (3 x 10(-5) M), but not by the D-enantiomer (3 x 10(-5) M). The potentiation was reversed by L-arginine (3 x 10(-4) M). The neurogenic vasoconstriction of mesenteric arteries was also augmented by capsaicin, but to a lesser extent than that induced by N omega-nitro-L-arginine. Indomethacin (10(-5) M) did not affect TNS-induced vasoconstriction. These findings suggest that nerve-derived nitric oxide or a related substance may play a greater role than do capsaicin-sensitive vasodilator transmitters in neurogenic regulation of mesenteric arterial tone in the monkey. The transmitter mechanisms for vasodilation in mesenteric circulation vary among species.