VOLATILE ANESTHETICS DECREASE PERISTALSIS IN THE GUINEA-PIG URETER

Background: The origin of renal dysfunction associated with anesthesia and surgery is complex and incompletely understood. The effects of the volatile anesthetic agents isoflurane, enflurane, and halothane on the renal pacemaker and ureteral peristalsis may play an important role. Methods: Guinea pig ureter and pelvis were dissected and placed in a sample chamber that allowed immersion in a temperature-controlled bath with gas (O-2 with or without volatile agent) bubbled through the chamber continuously. The baseline frequency and amplitude of peristaltic contractions were measured on a polygraph recorder. The preparations were then exposed to up to 4 vol% volatile agent incrementally to generate a cumulative dose-response curve, and the subsequent frequency of peristaltic contractions was determined. The concentration of the volatile agent in solution was measured by gas chromatography. Results: There was a significant dose-related decrease in the frequency of ureteral contractions for all three agents. A statistical model relating percentage baseline frequency to millimolar concentrations of volatile anesthetics showed that halothane produced a more pronounced decrease in frequency than did isoflurane or enflurane. However, the decrease was directly related to the MAC multiples and did not differ for the three agents. Conclusions: Ureteral peristaltic contractions are decreased in a dose-dependent manner by enflurane, halothane and isoflurane.