Spasmolytic action of verapamil, D600 and cinchocaine on the rat vas deferens.
The inhibitory action of verapamil, D600 and a local anesthetic, cinchocaine (CE) was studied on the isolated rat vas deferens. All three drugs inhibited norepinephrine (NE) and KCl dose-response curves in a concentration-dependent manner. Verapamil and D600 were approximately equivalent in their inhibitory effect but were significantly more potent (p < .05) than CE. Cinchocaine enhanced NE dose-response curves prior to inhibition at higher concentrations but did not affect KCl dose-response curves similarly. Inhibition of NE dose-response curves by CE and low concentrations of D600 showed significant negative correlation with the concentration of calcium in the medium. However, inhibition caused by high concentration of D600 (1 X 10(-5) M0 was unaffected by a 10-fold increase in calcium concentration. Contractile responses of the vas deferens to single doses of NE (1 X 10(-4) M) or KCl (40 mM) comprise of an initial fast (F) component and a slow (S) component. The inhibition of the F-component of NE- and KCl-induced responses by D600 and CE was inversely related to the concentration of calcium. Inhibition of the S-component of NE-induced respnses by both drugs was not correlated with calcium levels in contrast to that of KCl-induced responses where the inhibition showed significant negative correlation with the calcium content of the medium. Our results indicate D600 differs from CE in its effects on response to NE but that it is qualitatively similar to CE in its inhibition of KCl-induced responses.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003992:Dibucaine / Q000494:pharmacology*; D005711:Gallopamil / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D010276:Parasympatholytics; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D014649:Vas Deferens / Q000187:drug effects; D014700:Verapamil / Q000031:analogs & derivatives* / Q000494:pharmacology*
D010276:Parasympatholytics; D005711:Gallopamil; D014700:Verapamil; D003992:Dibucaine; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine