Sevoflurane but not isoflurane can reduce prostacyclin production of endothelial cells:

Sevoflurane and the feto-placental vasculature: the role of nitric oxide and vasoactive eicosanoids

BACKGROUND

The effects and mechanisms of action of volatile anesthetics on the feto-placental vasculature are not known. We aimed to quantify the vasoactive effects of sevoflurane and determine the role of nitric oxide (NO) and of vasoactive eicosanoids in mediating these effects in isolated human chorionic plate arterial rings.

METHODS

Quadruplicate ex vivo human chorionic plate arterial rings were used in all studies. Series 1 quantified the vasodilation produced by sevoflurane in rings preconstricted with the thromboxane analog U46619. Series 2A-C examined the role of NO in sevoflurane-mediated vasodilation. In separate experiments, we examined the potential for the nonspecific NO inhibitors, L-NAME, L-nMMA, and the inactive D-NAME, to modulate the vasodilation produced by sevoflurane. Series 2D determined whether sevoflurane altered vascular smooth muscle sensitivity to exogenous NO. Series 3A-D examined the role of vasoactive eicosanoids in sevoflurane-mediated vasodilation. In separate experimental series, we examined whether the nonspecific cyclooxygenase inhibitor, indomethacin, or the 5-lipoxygenase inhibitor, nordihydroguaiaretic acid, modulated sevoflurane-mediated vasodilation.

RESULTS

Sevoflurane produced dose-dependent vasodilation of preconstricted chorionic plate arterial rings, with mean ring vasodilation increasing from 15 +/- 7% at 2% sevoflurane to 67 +/- 17% (mean +/- sd) at 8% sevoflurane. Blockade of NO synthase did not attenuate the vasodilator effects of sevoflurane. Sevoflurane did not alter smooth muscle sensitivity to NO. Indomethacin augmented sevoflurane vasodilation at 10(-5) M, but not at 10(-6) M. Conversely, nordihydroguaiaretic acid attenuated sevoflurane-mediated vasodilation at 3 x 10(-6) M but not at 3 x 10(-7) M.

CONCLUSIONS

Sevoflurane was a vasodilator in the feto-placental vasculature in this in vitro model. Sevoflurane-mediated vasodilation is NO and cyclooxygenase-independent and appears to be mediated in part via a lipoxygenase generated vasodilator eicosanoid.

Sevoflurane promotes endothelium-dependent smooth muscle relaxation in isolated human omental arteries and veins

Anesthesia with sevoflurane is accompanied by vasodilatation. This could be due to the effects of sevoflurane on endothelium-dependent relaxation. We measured muscle tension of isolated human omental arteries and veins in response to substance P or glyceryl trinitrate in the presence of sevoflurane (0%, 1%, 2%, or 4%). Vascular levels of guanosine 3', 5'-cyclic monophosphate were measured with enzyme-linked immunosorbent assay. Substance P induced an endothelium- and concentration-dependent relaxation in omental vessels that was not affected by sevoflurane. In the presence of L-N(G)-nitroarginine methyl ester (nitric oxide synthase inhibitor), KCl (prevention of hyperpolarization), or both, sevoflurane at 4% enhanced the relaxation in the arteries (P < 0.05). In the vein segments, the relaxation was enhanced by sevoflurane at 4% in the presence of KCl and 2% and 4% in the presence of both L-N(G)-nitroarginine methyl ester and KCl (P < 0.05). The glyceryl trinitrate-induced endothelium-independent relaxation was enhanced by sevoflurane at 4% in both artery and vein segments (P < 0.05). Substance P increased the levels of guanosine 3', 5'-cyclic monophosphate similarly in the presence and absence of sevoflurane. These results show that sevoflurane, in contrast to its effect in animal models, promotes endothelium-dependent relaxation in human omental arteries and veins via an enhancement of the smooth muscle response to relaxing second messengers.