the possible mechanisms through which propranolol might act were considered to be ( 1 ) indirect effect of altered oxygen supply vs. demand , effect by reducing heart rate and reducing cardiac output due to the drug 's function as a beta blocker , ( 2 ) direct cellular effect , i.e. , reducing myocardial substrate metabolism along with stabilization of cellular structure , and ( 3 ) increase collateral circulation to the subendocardium .
C0033497
propranolol
C0428977
reducing heart