Renal calyceal and pelvic contraction rhythms.

An experimental study of the porcine multicalyceal pacemaker system was undertaken. In particular, the characteristic rhythmicities of in situ calyces were examined as well as rhythmicities between the calyceal system and the renal pelvis using pig kidneys perfused ex vivo via the renal artery. The temporal and spatial organization of calyceal and renal pelvic contraction rates were evaluated by simultaneously recording pressure from the renal pelvis and from three calyces. The results obtained from 15 kidneys indicate that the upper, middle, and lower calyces contract rhythmically at the essentially equal rates of 12.8 +/- 2.4, 14.0 +/- 1.6, and 13.06 +/- 2.3 min-1. The interaction between the activities of different calyces was analyzed by measuring the phase of individual calyceal contractions. Phase locking, coordination of contraction and phase oscillation, systematic fluctuations, or divergence of phase were obtained in most preparations, indicating the existance of a mechanism of coherent intercalyceal coupling. During periods in which phase locking occurred, pelvic contractions were related to all of the observed calyceal regions. When phase oscillation was present, the region of calyceal system evidencing a higher frequency was associated with pelvic contraction, whereas in the absence of calyceal coupling renal pelvic contractions could not be correlated to calyceal activity.