Membrane potential measurements in cultured intestinal villi

Fragmented epithelia of newborn rat small intestine were successfully cultured for periods of up to 4 weeks. Stable intracellular recordings of membrane potential were obtained from these cultured cells. Membrane resting potential varied according to cell location along a villus. The potentials rangged from -70 to - 15 mV, being highest at the tip of the villus. The mean resting potential and membrane resistance were -72.4 mV and 8.6 M omega, respectively. The membrane potential was markedly dependent on the extracellular K+ concentration ([K] 0), but not significantly on [Na] 0 and [Cl] 0. Deprivation of Ca2+ from the surrounding medium depolarized the membrane by 20 mV. When the cells were cooled down to 6 degrees C, membrane potential was reduced by 40 mV. Based on these data, basic mechanisms underlying the resting potential are discussed in connection with cell differentiation or maturation.