Influence of papaverine on bethanechol or OP-CCK stimulation of feline colonic muscle.

Papaverine relaxes smooth muscle from various organ systems throughout the body. The purpose of this study was to determine the effects of papaverine on colonic smooth muscle from the transverse colon of the cat. Myoelectrical activity was recorded with monopolar glass pore electrodes. Papaverine was administered alone and simultaneously with bethanechol or the octapeptide of cholecystokinin. Higher concentrations of papaverine (10(-4) M, 10(-5) M) abolished both slow-wave activity and migrating spike bursts. Lower concentrations of papaverine (10(-6) M) had no effect on slow waves or the migrating spike burst. Bethanechol (10(-6) M) or OP-CCK (4 x 10(-9) M, 4 x 10(-10) M) stimulated spike activity (p < 0.001). Papaverine (10(-6) M had a minimal effect on the increase in spike activity that occurred after octapeptide of cholecystokinin in a concentration of 4 x 10(-10) M (p < 0.05). Papaverine had no effect on the stimulation of the colonic smooth muscle by 4 x 10(-10) M octapeptide of the colonic smooth muscle by 4 x 10(-9) M octapeptide of cholecystokinin. These studies show that (a) papaverine can inhibit smooth muscle myoelectrical activity, (b) papaverine is a potent inhibitor of cholinergic stimulation of colonic smooth muscle, but (c) papaverine has a minimal effect on octapeptide of cholecystokinin stimulation of the isolated colonic smooth muscle.