Ca2+ release from isolated sarcoplasmic reticulum of guinea‐pig psoas muscle induced by K+‐channel blockers

Abstract

A Ca2+‐sensitive electrode was used to measure the Ca2+ concentration of the medium containing the heavy fraction of the fragmented sarcoplasmic reticulum (SR) prepared from guinea‐pig psoas muscle. Among K+‐channel blockers tested, 4‐aminopyridine (4‐AP), tetraethylammonium (TEA) and charybdotoxin elicited Ca2+ release from the SR, but apamin and glibenclamide did not. These results suggest that a reduction of SR K+ conductance leads to Ca2+ release from the SR. 1992 British Pharmacological Society