Procaine-induced contraction in vein and its modification by drugs

Procaine (or lidocaine) contracted whole segments of the rhythmically contracting anterior mesenteric vein (AMV) of the cat and rat in vitro. Autonomic blocking drugs, antihistamines, and antiserotonin agents were ineffective in reducing either the spontaneous activity of the vein or the procaine-induced contraction. Only those agents which abolished the spontaneous activity of the AMV prevented the procaine-induced contraction. It is suggested that conditions which permit action potential production in the AMV may be required for procaine-induced contractions to occur.