The effect of secretin on sodium ion absorption by the isolated human gallbladder

Sodium ion (Na+) transport, a principal function of the gallbladder epithelium, was studied by measuring the flux of 22Na across isolated human gallbladder mucosa maintained in a modified 'Ussing' flux chamber. Tissue was obtained from cholecystectomy specimens in symptomatic patients with cholelithiasis. Out of 26 gallbladders studied, 13 had a net Na+ flux from mucosa to serosa which indicated active Na+ absorption. The hormone secretin, when added to the serosal fluid, reversed the direction of net flux in these gallbladders and caused a secretion of Na+ from serosa to mucosa. These results suggest that secretin may be involved in the physiological regulation of fluid transport in the human gallbladder, and also suggest a possible role for this hormone in gallbladder emptying.