Dynamics of upper urinary tract. I. An electrophysiologic in vivo study of renal pelvis in pigs: method and normal pattern.

Under halothane anesthesia, peroperative electromyography of the pelvis and ureter together with intrapelvic pressure and urine flow were recorded in 11 pigs; the electromyography was by bipolar extracellular leads. Pressure waves of low amplitude, synchronous with action potentials from leads placed most proximally in the pelvis, preceded action potentials registered by distally placed leads. Transmission of the action potentials from the pelvis to the ureter took place with a constant transmission velocity but the transmission ratio varied from 1:1 to 6:1. Ureteral electric activity was time-related to the urine bolus. The transmission velocity was smaller in the pelvis than in the ureter and seemed to accelerate caudally. Thus, there is electromyographic evidence that the renal pelvis controls ureteric activity and that this pacemaker function is mediated high up, most proximally, in the renal pelvis.