Abstract
The present study investigated the effects of repetitive exposure to a select group of biogenic amines (epinephrine, norepinephrine, histamine, and serotonin) on pulmonary vascular reactivity by constructing and analyzing a set of four sequential cumulative dose-response curves to one biogenic amine in the isolated blood-perfused left lower lobe of the cat lung in vivo. The dose-response curves were obtained under conditions of constant flow, insuring that the observed pressure changes in the lobe were pressor responses resulting from vasoconstriction rather than flow-related changes. Histamine and epinephrine demonstrated a progressive loss of initial vasoconstrictor activity, whereas the responses to serotonin remained unchanged after repetitive exposure. Norepinephrine demonstrated two different patterns of response, depending on the dose range employed; norepinephrine (0.068-2.27 nmol/ml) demonstrated a loss of the original vasoconstrictor activity, in a pattern similar to histamine and epinephrine, while higher doses of norepinephrine (0.34-9.1 nmol/ml) demonstrated no change in activity with a left shift in the concentration at which the maximal responses occurred, suggesting an increase in sensitivity as a result of repeated exposure. These results were obtained in the absence of significant alterations of arterial blood gases, changes in base-line tone in the experimental left lower lobe, or the development of severe pulmonary edema. These data suggest that only the agents that are capable of stimulating antagonistic vasoconstrictor and vasodilator receptors demonstrated a loss of pulmonary vasoconstrictor activity, which may result from a functional shift in the balance of antagonistic receptor activity with continued exposure.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
15 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献