Does halothane or isoflurane affect hypoxic and post-hypoxic vascular response in rabbit aorta?
BACKGROUND
Halothane and isoflurane affect differently endothelium-dependent and -independent vasorelaxation at 95% O2. In addition, hypoxic vascular response might involve endothelium-dependent and -independent mechanisms. Therefore, we investigated, in rabbit aortic rings, 1) the influence of halothane and isoflurane on vasodilation at 95% O2 and on hypoxic-induced vasorelaxation at 0% O2 and 2) the influence of halothane and isoflurane on endothelium-dependent and -independent post-hypoxic vascular response.


METHODS
Endothelium-intact and endothelium-denuded rabbit aortic rings were used. Phenylephrine precontracted rings were exposed, at 95% O2, to acetylcholine (ACh, 10(-9) to 10(-4) M) or sodium nitroprusside (SNP, 10(-9) to 10(-4) M) in the presence or absence of anaesthetic at 1 or 2 MAC. Precontracted rings were also exposed to an acute reduction in O2 from 95% to 0% followed by an acute reoxygenation with 95% O2 in the absence or presence of anaesthetic at 1 or 2 MAC.


RESULTS
At 95% O2, halothane decreased endothelium-dependent relaxation to ACh, while endothelium-independent relaxation to SNP was decreased only at 2 MAC. Isoflurane did not modify ACh- or SNP-induced relaxation. At 0% O2, neither halothane nor isoflurane altered the hypoxic vascular relaxation. Post-hypoxic response was not changed either.


CONCLUSIONS
Our results indicate that halothane and isoflurane do not alter vascular hypoxic response in conductance arteries.
Haddad
E
E
Département de Pharmacologie, Centre Hospitalier Régional Universitaire de Lille, France.
Lebuffe
G
G
Boillot
A
A
Imbenotte
M
M
Vallet
B
B
D000109:Acetylcholine / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D001012:Aorta, Abdominal / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology; D006221:Halothane / Q000494:pharmacology*; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D007530:Isoflurane / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*
D018685:Anesthetics, Inhalation; D009599:Nitroprusside; D007530:Isoflurane; D000109:Acetylcholine; D006221:Halothane