The effect of age on halothane-induced alterations of contractility in isolated rat aorta.
Aging is implicated as a factor which increases the susceptibility to volatile anesthetic-induced depression of the cardiovascular system. However, little is known regarding mechanisms responsible for this enhanced depression. Current experiments examined the effects of 1.2 and 2.4 vol.% halothane on norepinephrine-induced contractility in endothelium-intact and -denuded aortic preparations isolated from 4-, 14-, and 24-month-old Fisher-344 rats. Prior to exposure to halothane, endothelium removal significantly enhanced the sensitivity to norepinephrine in all age groups without altering the maximum tension. Additionally, in endothelium-intact preparations, increasing age from 4 to 24 months decreased the sensitivity to norepinephrine. Exposure to 2.4 vol.% halothane caused a significant decline in the maximum tension generated in response to norepinephrine in all groups. There were no differences in the amount of depression seen with 2.4 vol.% halothane either within age groups or between endothelium-intact and -denuded preparations of the same age. Halothane at 1.2 vol.% caused a significant reduction in the amount of tension generated in the 4-month-old, endothelium-denuded group. However, all age groups with and without endothelium tended to decrease to a similar degree at 1.2 vol.% halothane, and there were no differences either within age groups or between endothelium-intact and -denuded preparations of the same age. In the 4- and 14-month-old endothelium-intact groups, both 1.2 and 2.4 vol.% halothane decreased the sensitivity to norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)
Brian
J E
JE
Department of Anesthesiology, University of Arkansas for Medical Sciences, Little Rock 72205.
Slaven
J S
JS
Kennedy
R H
RH
Seifen
E
E
D000375:Aging / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects*; D006221:Halothane / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D014661:Vasoconstriction / Q000187:drug effects*
D006221:Halothane; D009638:Norepinephrine