Abstract
The rates of fluid transfer across human gallbladders obtained at cholecystectomy for cholelithiasis were determined by the measurement of weight changes of everted preparations under controlled conditions. Active transport of fluid from the mucosal to the serosal surface was indicated since weight gain occurred with the same solution on both sides of the membrane and against hydrostatic, osmotic, and potential differences. With respect to sodium, the fluid transferred was isotonic to the bathing solutions. Metabolic inhibitors and temperature extremes inhibited weight gain. In addition, muscle contractions in this in vitro preparation were related to the rates and direction of fluid movement. Cholecystokinin increased muscle activity and caused weight loss in preparations that previously had gained weight. Norepinephrine caused weight gain or increased weight gain in all preparations tested. The direction of net fluid movement in the isolated everted human gallbladder was determined by the opposing forces of active mucosal transport and a filtration pressure generated by muscle contractions.