Alteration in myocardial oxygen balance during exercise after beta-adrenergic blockade in dogs

Publisher Website
Google Scholar
Abstract
The effects of .beta.-adrenergic blockade upon myocardial blood flow and O2 balance during exercise were evaluated in 8 conscious dogs that were instrumented for chronic measurements of coronary blood flow, left ventricular pressure, aortic blood pressure, heart rate and sampling of arterial and coronary sinus venous blood. The administration of propranolol (1.5 mg/kg i.v.) produced a decrease in heart rate, peak left ventricular (LV) dP/dt [rate of pressure change], LV (dP/dt)/P [the quotient of the rate of pressure change to developed pressure], and an increase in LV end-diastolic pressure during exercise. Mean coronary blood flow and myocardial O2 consumption were lower after propranolol than at the same exercise intensity in control conditions. The O2 delivery-to-O2 consumption ratio and the coronary sinus O2 content were significantly lower. The relationship between myocardial O2 supply and demand is modified during exercise after propranolol, so that a given level of myocardial O2 consumption is achieved with a proportionally lower myocardial blood flow and a higher O2 extraction.

This publication has 0 references indexed in Scilit: