Neurohemodynamics of pulmonary edema. IV. Effect of systemic vasoconstriction and subsequent vasodilation on flow and pressures in systemic and pulmonary vascular beds.

T HE INFLUENCE of the tone of peripheral blood vessels on pulmonary vascular hemodynamics has been shown to be considerable. That is, sympathetic impulses to the peripheral vascular bed are capable of causing a striking rise in pulmonary vascular pressures even in the absence of pulmonary innervation (1-3) and also of causing a grossly observable increase of pulmonary blood volume (4). Conversely, it was found that blockade of sympathetic impulses to the systemic vascu lar bed produced a prompt decrease in pulmonary vascular pressures when the latter were initially elevated and also caused a decrease in pulmonary bl .ood volume ( 1-4). The data to be presented below were gathered in order to define more completely the hemodynamic changes that occur when the intracisternal injection of ‘fibrin’ is followed by elevations of systemic and pulmonary vascular pressures in the dog.