Calphostin c, a widely-used protein kinase c inhibitor, directly and potently blocks l-type ca channels. Hartzell, H. Criss, and Amber Rinderknecht. HeartCell Laboratory, Emory University School of Medicine, Department of Anatomy and Cell Biology, Atlanta, GA 30322-3030
APStracts 2:0381C, 1995.
Calphostin C is a widely-used inhibitor of protein kinase C: in the past 4 years at least 350 articles have been published using this drug as a selective inhibitor of protein kinase C. In this paper, we show that calphostin C also potently inhibits cardiac L-type Ca channels by a mechanism that does not involve changes in cAMP levels or dephosphorylation. The inhibition requires illumination by visible light during exposure to calphostin C. The Ca current that remains after partial inhibition of ICa has the same voltage dependent characteristics as the control current.

Received 8 September 1995; accepted in final form 17 October
1995.
APS Manuscript Number C545-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95