Abstract
In supine anesthetized rats, two cannulae were inserted into a unilateral ureter near the kidney and urinary bladder, respectively. Fluid from a reservoir placed approximately 27 cm above the rat was infused into the ureter lumen through the cannula near the kidney, and the resulting peristaltic pressure signals were measured from the cannula near the bladder. When drugs acting on ion channels were applied from the ureter lumen and their effects on the peristaltic pressure signals were studied, the K+ channel opener BRL 38227 (1×10-4M and 1×10-3M) was found to decrease the frequency dose-dependently. However, the K+ channel blockers glibenclamide and 4-aminopyridine at 1×10-3M did not affect peristaltic movement. Nifedipine (1×10-5M and 1×10-4M) decreased the frequency of peristalsis, but the effect was weaker than that of BRL 38227. Lidocaine at very high concentration (1.5×10-2 and 1.5×10-1 M) decreased the amplitude and increased the frequency of the peristaltic signals. These results indicate that the K+ channel opener has the most inhibitory effect on ureteral peristaltic function.
