Is reduced cardiac performance the only mechanism for myocardial infarct size reduction during beta adrenergic blockade?

Equal reductions in heart rate (44 beats·min−1) were obtained in cats by treatment with either the beta blocking agent timolol or alinidine, an agent claimed to cause bradycardia without interfering with beta adrenoceptor function. Infarct size was measured by staining with triphenyl-tetrazolium-chloride after 5 h of coronary occlusion and related to the area of hypoperfused myocardium as measured by autoradiography. Regional myocardial blood flow was measured by 15 μm radiolabelled microspheres. Compared with the control cats, in whom 87.4 (SEM2.2)% of hypoperfused myocardium developed into necrosis, timolol reduced infarct size to 65.8 (SEM 2.6)% (p