Responses of the Bronchial Veins in a Heart-Lung-Bronchial Preparation

Blood collected from the bronchial veins of a heart-lung-bronchial preparation consists of two components: (a) fraction from the bronchial arteries, and (b) pulmonary to bronchial shunt It is estimated that the latter is more than half of total bronchial venous flow. The pulmonary to bronchial shunt is reduced by procedures which increase pulmonary arterial pressure. An intrinsic nervous reflex mechanism is suggested to explain such a response, particularly because the bronchial veins are more sensitive than the bronchial arteries to the vasoconstrictor action of epinephrine and norepinephirine, and to the vasodilator action of isoproterenol. acetylchohine, histamine, and DMPP. Alterations in bronchial venous flow induced by such chemical agents are independent of bronchoconstriction or bronchodilatation.