Changes in Pulmonary Circulation in Experimental Model of Pulmonary Thromboembolism after Carvedilol Treatment

In experiments on isolated perfused rabbit lungs, we studied changes in the pulmonary microcirculation in response to carvedilol injection and after modelling pulmonary thromboembolism under conditions of α₁- and β_1,2-adrenoceptor blockade with this drug. Carvedilol had mainly vasodilator effects on the pulmonary arterial vessels; the pulmonary venous resistance increased and the capillary filtration coefficient remained unchanged under these conditions. In case of pulmonary thromboembolism against the background of carvedilol treatment, the increase in precapillary resistance and the capillary filtration coefficient was more pronounced that in the control, but the postcapillary resistance increased to a lesser extent. The increase in the capillary filtration coefficient is a result of elevated precapillary resistance and enhanced endothelial permeability.