Dynamics of upper urinary tract. III. The activity of renal pelvis during pressure variations

In one phase of an analysis of renal pelvis activity in pigs "in vivo," controlled pressure changes were induced in the pelvis and electromyogram registrations were taken from both pelvis and ureter. Animals were anesthetized and the changes in intrapelvic pressure were effected by drainage or infusion via a catheter introduced into the pelvis through the parenchyma of the kidney. Frequency of pelvic activity increased temporarily under pressure increase and reduced temporarily under pressure fall. These phenomena were more emphatic when rapid pelvic pressure rise was induced by infusion. The observations lend weight to previous observations of changing pelvic activity during pressure and diuresis change, and also support the hypothesis that pelvic function is a stretch response, i.e., that the smooth muscle of the pelvis reacts just as does other smooth muscle. Observation of cessation in ureter activity during drainage while pelvic activity continues suggests that, under normal conditions, ureteric activity depends not on conduction of a pelvic impulse alone, but on a combination of such an impulse with a urine bolus.