Comparative studies on normal ureteral peristalsis in dogs, guinea-pigs and rats

Summary

Ureteral peristalsis was measured in unanaesthetized dogs and in isolated preparations of dogs and rats. The normal pacemaker is localized — as in the guinea-pig — in the proximal parts of the renal pelvis. The frequency distribution of peristaltic intervals is multimodal, with harmonic relations between the mode values. In the unanaesthetized dog, the preferred values for the single modes are around 5–7 and 10–15 sec. The mode in the range of 10–15 sec is more likely to be the indicator of the normal basic value. 4–6/min can therefore be taken as the basic frequency of canine ureteral peristalsis. In isolated pyeloureter preparations of the rat, after an initial overactive phase, a steady state with a peristaltic frequency of 5/min at 35°C was reached. This steady-state value can be taken as the indicator of the normal basic peristaltic rate of the rat (6/min at body temperature). In comparison with observations in the guinea-pig (Golenhofen and Hannappel, 1973), the theory is derived that in all species the basic peristaltic rate of ureter is determined by, and coordinated with, a species-specific intrinsic frequency of the smooth muscle system which has its clearest manifestation in stomach peristalsis. The variability of ureteral peristaltic rate is greater in dogs and rats than in guinea-pigs.