An experimental study about spontaneous voltage gradient, total transepithelial resistance and short-circuit current is made on different amphibian and mammalian epithelia. The dissected tissue is placed between two cubic chambers. The biological membrane divides two electrolytic oxigenated-solutions at 20°C and pH 7.4 conditions. A multimeter measures the voltage difference between the solutions, then 6?? for transepithelial resistance calculation. Thereafter a 9 – 56 V outer electromotive force and a potential divider are placed in series with the tissue to adjust and maintain zero potential, in order to measure the short-circuit current. Significant differences with 0.01level confidence were found in the electric epithelial parameters of the frog skin and urinary bladder and in the rabbit and rat proximal colon, urinary bladder and gallbladder. While [Na+] decrease from 107 to 0.375 mM minimized the short-circuit current in the frog skin, 100 mU/ml vasopressin in the serosal solution significantly increased it by 62%. The frog urinary bladder transepithelial resistance increased by means of pH decrease from 7.4 to 6.0 in the serosal solution and also by 10 mM amiloride in the mucosal solution. Neither the total transepithelial resistance nor the shor-circuit current significantly changed in the rabbit urinary bladder exposed to amiloride.