Clonazepam and diltiazem both inhibit sodium-calcium exchange of mitochondria, but only diltiazem inhibits the slow action potentials of cardiac muscles.
Clonazepam, up to concentrations of 5 x 10(-5) M produced only 15% inhibition of contraction without effecting isoproterenol-induced slow action potentials (APs) of guinea pig papillary muscles. On the other hand, 10(-6) M diltiazem completely inhibited both slow APs and contractions. Both clonazepam and diltiazem inhibited Na+-induced Ca2+ release from isolated mitochondria. The half-maximum effect of clonazepam and diltiazem occurred at 7 and 8 x 10(-6) M respectively. The results suggest that clonazepam more specifically inhibits the Na+-induced Ca2+ release process of mitochondria.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology*; D001570:Benzodiazepinones / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002998:Clonazepam / Q000494:pharmacology*; D004110:Diltiazem / Q000494:pharmacology*; D006168:Guinea Pigs; D007545:Isoproterenol / Q000494:pharmacology; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D009200:Myocardial Contraction / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*
D001552:Benzazepines; D001570:Benzodiazepinones; D002998:Clonazepam; D012964:Sodium; D004110:Diltiazem; D007545:Isoproterenol; D002118:Calcium