Effects of vasodilator drugs on normal and serotonin-constricted pulmonary vessels of the dog.

RUDOLPH, ABRAHAM M., M. DAVID KURLAND, PETER A. M. AULD AND MILTON EL PAUL. Effects of vasodilator d ugs on normal and serotonin-constricted pulmonary vessels of the dog. Am. J. Physiol. I g7(3) : 6 I 7-623. I gsg.---Previous studies of the action of vasodilator drugs on the pulmonary blood vessels have yielded inconclusive results. Studies on the effects of continuous infusion of vasodilator agents, first on normal pulmonary vessels, and then on serotonin-constricted pulmonary vessels, suggest that the response of the pulmonary vasculature is dependent on the degree of vasoconstrictor tone present. Consistent vasodilator responses to acetylcholine, histamine and adenosinetriphosphate were elicited when the pulmonary vessels were constricted by continuous infusion of serotonin. Pulmonary vasomotor responses to drugs occur in both the small pulmonary vessels and the large pulmonary veins.