Persistent enhancement of potassium-induced responses of the rat vas deferens by desipramine.

The effect of desipramine on the cumulative dose-response curves of noradrenaline and potassium (K+) was examined on the isolated rat vas deferens. An exposure of 10 min to 10(-7) M desipramine caused a leftward shift and an increase in the maximum response of cumulative dose-response curves of noradrenaline. Desipramine (10(-7) M), in contact with the tissue for 10 min, enhanced responses to cumulative additions of K+ without causing a consistent change in threshold concentrations. Wash-out of desipramine resulted in a rapid loss of enhanced maximum response to noradrenaline while the maximum response to K+ did not show any decrease for up to 120 min after wash-out of drug. One possible explanation for the persistent enhancement of K+-induced responses may be that desipramine causes postjuntional changes which selectively influence contractile responses of this tissue to K+.