Does halothane or isoflurane affect hypoxic and post-hypoxic vascular response in rabbit aorta?

Background: Halothane and isoflurane affect differently endothelium-depende nt and -independent vasorelaxation at 95% O-2 In addition, hypoxic Vascular response might involve endothelium-dependent and -independent mechanisms. Therefore, we investigated, in rabbit aortic rings, 1) the influence of hal othane and isoflurane on Vasodilation at 95% O-2 and on hypoxic-induced vas orelaxation at 0% O-2 and 2) the influence of halothane and isoflurane on e ndothelium-dependent and -independent post-hypoxic vascular response. Methods: Endothelium-intact and endothelium-denuded rabbit aortic rings wer e used. Phenylephrine precontracted rings were exposed, at 95% O-2, to acet ylcholine (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. Precont racted rings were also exposed to an acute reduction in O-2 from 95% to 0% followed by an acute reoxygenation with 95% O-2 in the absence or presence of anaesthetic at 1 or 2 MAC. Results: At 95% O-2, halothane decreased endothelium-dependent relaxation t o ACh,while endothelium-independent relaxation to SNP was decreased only at 2 MAC. Isoflurane did not modify ACh- or SNP-induced relaxation. At 0% O-2 , neither halothane nor isoflurane altered the hypoxic vascular relaxation. Post-hypoxic response was not changed either. Conclusion: Our results indicate that halothane and isoflurane do not alter Vascular hypoxic response in conductance arteries. (C) Acta Anaesthesiologica Scandinavica 44 (2000).