INHIBITION OF K-INDUCED TONIC CONTRACTION IN VAS DEFERENS OF GUINEA PIG BY CHLORPROMAZINE AND ITS FREE RADICAL

Abstract

Inhibitory effects of chlorpromazine (CP) and its free radical (CP•) on the tonic component of the K-contraction of vas deferens isolated from guinea pig were studied by the Magnus method. CP and CP. were equally effective at concentrations higher than 2×10^-7 g/ml for selective inhibition of the tonic component in neutral media (pH 7.4). The effect of CP• was 100 times greater than that of CP in acidic media (pH 5.0). These findings can be explained in terms of the increased stability of CP•, since the absorption spectral analysis showed that CP• was apparently stable in acidic media. Among reducing agents studied, 2-mercaptopropionylglycine was the most potent in restorative activity for the above inhibition.