9-METHYL-7-BROMOEUDISTOMIN-D INDUCES CA2-RETICULUM( RELEASE FROM CARDIAC SARCOPLASMIC)

9-Methyl-7-bromoeudistomin D (MBED), the most powerful caffeine-like r eleaser of Ca2+ from skeletal muscle sarcoplasmic reticulum, induced C a2+ release from the cardiac sarcoplasmic reticulum, MEED (5 mu M) and caffeine (I mM) caused rapid Ca2+ release from the fragmented cardiac sarcoplasmic reticulum in a Ca2+ electrode experiment. [H-3]MBED boun d to a single class of high-affinity binding sites in cardiac sarcopla smic reticulum membranes (K-d = 150 nM). These results suggest that ME ED binds to a specific binding site on cardiac sarcoplasmic reticulum membranes to induce Ca2+ release from the cardiac sarcoplasmic reticul um. Thus, MEED is a useful probe for characterizing Ca2+ release the c hannels nor only in skeletal sarcoplasmic reticulum but also in cardia c sarcoplasmic reticulum. (C) 1998 Elsevier Science B.V. AU rights res erved.