Initiation and propagation of canine renal pelvic peristalsis

A new in vitro method was employed which enabled detailed examination of the initiation and propagation of the peristaltic contraction of the renal pelvis and ureter. Both the kidney and its attached ureter were carefully removed and the renal parenchyma concealing the renal pelvis and calyces removed under the dissection microscope. At the pelvicalyceal border, ripple-like peristaltic contraction of a constant frequency were observed. At the same time, electromyograms with a slow rising phase were recorded at constant intervals from the pelvicalyceal border, leading us to deduce that these might represent pacemaker potentials. The discharge interval of electromyograms recorded at both the center of the pelvis and the pelviureteric junction were found to be a multiple of the 'pacemaker' interval. Electrical activity (peristalsis) arising from the pacemaker might be blocked at only the center of the pelvis but also at the pelviureteric junction.