SYMPATHETIC NERVOUS CONTROL OF THE PULMONARY VESSELS IN EXPERIMENTAL PULMONARY EMBOLISM

Abstract

In the acute stage of the pulmonary embolism, so-called Bezold-Jarisch-like reflexes are brought about which include bradycardia, systemic hypotension, pulmonary hypertension and hyperventilation following hypoventilation. There have been many works which dealt with pulmonary hypertension induced by experimental pulmonary embolism that are ascribed to the mechanical obstruction of the pulmonary vascular beds. But recently many investigators have revealed the possibility of concomitant pulmonary vasoconstriction along with the mechanical obstruction. Dexter et al showed in 1963 that arteriolar embolization caused active vasoconstriction in opposition to prearteriolar embolization by comparing the embolized vascular areas with grades of pulmonary hypertension when different sizes of emboli were injected into the pulmonary arteries. Bernthal and Aviado utilized the perfusion technique with constant pressure and constant flow respectively in order to measure the active vasoconstriction and emphasized that an intrinsic or sympathetic regulation of the vasoconstriction plays an important role in pulmonary embolism. The possibility of vasoconstriction in pulmonary embolism has been re-examined in this study by the method of constant flow perfusion of the left lower lobe and the rapid freezing method.