the proarrhythmic action of isoproterenol was primarily the result of a beta 1-receptor-mediated tachycardia rather than via a free radical-mediated process , since it was prevented competitively by the beta 1-receptor antagonist metoprolol , but not by the free radical scavengers mannitol , superoxide dismutase , and catalase .
C0022245
isoproterenol
C0039231
tachycardia