Cholelithiatic human gallbladders in vitro fail to respond to cholecystokinin but are responsive to carbachol, histamine, or electrical stimulation

Abstract

The present investigation was undertaken to delineate the in vitro responsiveness of cholelithiatic gallbladders to cholecystokinin (CCK) and compared with those evoked by carbachol, histamine, or electrical stimulation. Gallbladder muscular strips (2-3 mm wide and 15-20 mm long) from patients undergoing cholecystectomy were used for recording the in vitro contractions evoked by electrical and chemical (carbachol, histamine, or cholecystokinin) stimulation. Stimulation of strips with trains of pulses (5-msec duration, 70 V at 100 Hz) of varying train durations (0.01 to 9 sec) elicited duration-dependent increase in the amplitude of contractions and the maximal contractions were seen with 5 sec. Atropine (0.4 μM) significantly attenuated these contractions, leaving about 34% of contractions, which in turn was abolished by xylocaine. Carbachol produced a concentration-dependent (0.004-0.4 μM) increase in force of contraction and the maximal response was seen at 0.4 μM and abolished by atropine (0.4 μM). Histamine also produced contractions and the maximal contractions were about 35% of the maximal carbachol response. Histamine-induced contractions were not abolished by atropine but were abolished by xylocaine. CCK up to 10 μM failed to evoke any contraction, even though the strips were responsive to carbachol. The results indicate that cholelithiatic gallbladders exhibited responses to electrical stimulation through cholinergic and histaminergic plexuses and they were insensitive to CCK.