Sites of Action for Hypercapnia, Hypoxia, Acidosis and Histamine in the Blood Vessels of the Isolated Cat Lung
Date of Award
Dissertation - Restricted
Doctor of Philosophy (PhD)
James J. Smith
It has been known from the early part of this century that the pulmonary circulation is capable of increasing its resistance to blood flow when histamine was injected into it or when the lung was ventilated with gas mixtures containing low oxygen concentrations. However, it was not until the middle part of the century that the effects of hypercapnia and acidosis were considered as important regulators of pulmonary vascular resistance. Since that time interrelations between drugs and gaseous alterations have been found.
Interest in the pulmonary vascular sites of action for various vasoactive agents has stimulated research interests in recent years, so it is in this area where much controversy is now centered. One reason for the lack of agreement among investigators regarding pulmonary vascular sites of action is that a variety of techniques and preparations have been used. Most previous reports concerning sites of action have been based on work with the isolated-perfused cat lung. For this reason, it was the preparation of choice in the present study to determine the active sites of four pulmonary vasoconstrictors; hypercapnia, hypoxia, acidosis and histamine.