Gallbladder pressure, compliance, and hysteresis during cyclic volume change

The gallbladder has both storage and contractile properties, but is pressure-volume characteristics have not been fully described. We studied gallbladder pressure, compliance, stress relaxation, and the work performed during infusion-withdrawal of fixed volumes of bile at increments of base-line volume under halothane anesthesia in 13 dogs. Two cannulae were inserted in the gallbladder fundus: one for cyclic infusion-withdrawal of bile, and one for pressure monitoring. Following ligation of the cystic duct, the gallbladder was fully aspirated and then filled to successive predetermined base-line volumes (15, 20, 25, 30, or 35 mL). At each base-line volume, 5 mL of bile was infused and withdrawn at 2.47 mL/min. Studies were performed under basal conditions and with cholecystokinin octapeptide (CCK) infusion (10 or 30 ng.kg-1.h-1iv). Pressure was measured at base-line, after infusion, and after withdrawal. Compliance during infusion (delta V/delta P) was calculated for each cycle. Stress relaxation was defined as the difference between base-line pressure and any reduction in pressure after withdrawal. Hysteresis, the difference between work of infusion and work of withdrawal, was calculated. The results were such that base-line, end-infusion, and end-withdrawal pressures; work of infusion, work of withdrawal, and hysteresis; and stress relaxation all increased significantly with increases in the predetermined base-line volumes (p less than 0.001). Compliance decreased significantly (p less than 0.001) with increasing base-line volume. CCK at 10 ng.kg-1.h-1iv had no effect, but infusion of CCK at 30 ng.kg-1.h-1 significantly (p less than 0.05) increased pressure and work, decreased compliance, and increased stress relaxation compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)