Acetylcholine vasodilation of resistance vessels in vivo may not entirely depend on newly synthesized nitric oxide.

Blood flow was measured in denervated hind limbs of pentobarbital-anesthetized cats. Intravenous NG-methyl-L-arginine, 3-30 mg/kg did not affect the magnitude or duration of vasodilation produced by intra-arterial acetylcholine. Intra-arterial NG-methyl-L-arginine induced hind limb vasoconstriction and reduced the duration but not the magnitude of the acetylcholine vasodilator response. The results suggest that acetylcholine-induced hind limb vasodilation may not entirely depend on newly synthesized nitric oxide.