Effects of oxyfedrin: a β-adrenoreceptor stimulant, on infarct size following acute coronary artery ligation

Regional left ventricular blood flow and the extent of myocardial ischaemia were studied after acute coronary artery occlusion in open-chest dogs before and after infusion of oxyfedrin, a β-adrenergic stimulant. Regional blood flow was measured with radioactive tracer microspheres and local tissue injury was estimated by the S-T segment elevation in epicardial electrocardiograms. Animals receiving oxyfedrin were divided into two groups: 1 and 2. Oxyfedrin was infused intravenously in a dose of 0.80 to 0.94 mg·kg−1 in dogs of group 1 and 1.45 to 1.60 mg·kg−1in dogs of group 2. The rate of infusion in the animals of both groups was 0.61 mg·min−1. Oxyfedrin caused further S-T segment elevation over ischaemic myocardium and increased the extent of ischaemic injury in group 1 dogs. Conversely, in this same group of dogs, the blood flow was unchanged in low flow regions (