The character of pulmonary and venous hemodynamics chahges in the experimental pulmonary thromboembolism and myocardial ischemia models

The pulmonary and venous hemodynamics changes were studied in the experimental pulmonary embolism and myocardial ischemia models in acute experiments on anesthetized rabbits in control and after the blockade of -adrenoceptors with phentolamine. After 1 min of pulmonary thromboembolism the pulmonary artery pressure and pulmonary vascular resistance increased, the pulmonary flow decreased; the superior vena cava flow decreased to a lesser extent than the inferior vena cava one. During 1 min myocardial ischemia the pulmonary artery pressure and flow decreased, pulmonary vascular resistance did not changed; the superior vena cava flow decreased more than the inferior vena cava one. In case of pulmonary thromboembolism after the blockade of -adrenoceptors the pulmonary artery pressure increased to the same level, as in control animals, the pulmonary vascular resistance was elevated to a lesser extent. The pulmonary artery flow, the venae cava flows and venous return decreased less than in control. In case of myocardial ischemia after the blockade of -adrenoceptors the pulmonary artery pressure decreased more, than in control animals, the pulmonary vascular resistance had tendency towards decrease, the venae cava flows and venous return decreased more than in control experiments.The differences of the changes of the pulmonary and venous circulation in cases of pulmonary embolism and myocardial ischemia were caused by activation of the adrenergic mechanisms.