Abstract

Verapamil inhibits slow channel activity in cardiac and vascular smooth muscle. Its action on nerve tissue is less clear. A series of experiments on isolated rat sciatic nerve was performed to evaluate verapamil's local anesthetic activity. The results indicate that DL-verapamil possessed significant frequency-dependent, fast channel (local anesthetic) blocking activity. An equal molar concentration of verapamil was found to be as potent as procaine in producing conduction block. Whereas ATP reversed procaine conduction block in vitro, ATP had no effect on the block induced by verapamil. The evidence suggests that verapamil possesses pharmacologic properties unrelated to slow channel inhibition.