Sodium ion (Na+) transport, a principal function of the gallbladder epithelium, was studied by measuring the flux of 22Na across isolated, inflamed human gallbladder mucosa maintained in a modified 'Ussing' flux chamber. Tissue was obtained from cholecystectomy specimens in symptomatic patients with cholelithiasis. 2. In 30 gallbladders studied, 57% had a net Na+ flux from mucosa to serosa (Na+ absorption), while 23% had a net Na+ flux from serosa to mucosa (Na+ secretion). The remaining 20% showed no overall net Na+ flux. 3. Indomethacin added to the serosal fluid reversed the direction of net Na+ flux in secreting gallbladders and caused an absorption of Na+. In Na+-absorbing gallbladders, indomethacin caused a slight reduction in Na+ absorption. No change in Na+ flux was induced in gallbladders with no initial net Na+ flux. 4. These results demonstrate that instead of absorbing Na+, some inflamed human gallbladders may secrete Na+. As this secretion can be reversed to the more usual absorption by indomethacin, it is likely that this secretion is mediated by prostaglandins.
