Evidence for an increase in membrane conductance during adenosine triphosphate-induced depolarization in the guinea-pig vas deferens

The effects of exogenously applied adenosine triphosphate (ATP) on the smooth muscle of guinea-pig vas deferens were studied with the double sucrose-gap method. ATP evoked a membrane depolarization which was associated with a decrease in the size of electrotonic potentials. Conditioning hyperpolarization induced by current application caused an increase in the magnitude of the ATP-induced depolarization; the larger the conditioning hyperpolarization, the greater the ATP-induced depolarization. These results are discussed with respect to the ionic mechanism of the electrical event in response to ATP in this tissue.