Electrical characteristics of the epithelial tissue and cells of the carp and frog gallbladder

: Transepithelial potential and resistance, the ratio of resistance of the apical to the basal cell membranes (Ra/Rb) were studied during transmural current clamps in isolated frog and fish gall-bladder (GB) with Ringer's solution on both sides. The findings show that: 1) the difference between the mucosal and serosal membrane potentials (MPs) was 3-8 mV as determined by transmural potential; 2) the ratio Ra/Rb depends on the MP value: it was less than 1 if MP was about 30 mV, and more than 1 if MP was over 30 mV; 3) outward and inward current clamps (about 20 microA/0.3 cm2) produced linear changes of MP on both apical and basal membranes; at high currents (40-60 microA/0.3 cm2) linear dependence is distorted especially for apical membrane whose conductance abruptly increases during current clamps.