Sevoflurane inhibits guanosine 5′-[γ thio]triphosphate-stimulated, Rho/Rho-kinase-mediated contraction of isolated rat aortic smooth muscle

Abstract

Background: The Rho/Rho-kinase signaling pathway plays an important role in mediating Ca2+ sensitization of vascular smooth muscle. The effect of anesthetics on Rho/Rho-kinase-mediated vasoconstriction has not been determined to date. This study is designed to examine the possible inhibitory effects of sevoflurane on the Rho/Rho-kinase pathway by measuring guanosine 5′-[γ-thio]triphosphate (GTPγS)-stimulated contraction and translocation of RhoA (one of the three Rho subtypes) and Rock-2 (one of the two Rho-kinase subtypes) from the cytosol to the membrane in rat aortic smooth muscle. Methods: GTPγS-induced contraction of rat aortic endothelium-denuded rings was measured using an isometric force transducer, and GTPγS-stimulated membrane translocation of RhoA and Rock-2 in smooth muscle cells was detected with Western blotting in the presence and absence of sevoflurane. Results: GTPγS (10-4 M) induced a sustained contraction, which was significantly inhibited by the Rho-kinase inhibitor, Y27632 (3 × 10-6 M). Before treatment with GTPγS, RhoA and Rock-2 were detected primarily in the cytosolic fraction. GTPγS (10-4 M) stimulated the translocation of RhoA and Rock-2 from the cytosol to the membrane, which was sustained for more than 60 min. Sevoflurane (1.7, 3.4, and 5.1%) concentration dependently inhibited the GTPγS-induced constriction of rat aortic smooth muscle with a reduction of constriction of 52-75% (P < 0.01, n = 8), and attenuated the translocation of RhoA and Rock-2 by 31-66% and 34-78%, respectively (P < 0.05-0.01, respectively; n = 4). Conclusion: The current findings show that sevoflurane depresses the GTPγS-stimulated contraction and translocation of both Rho and Rho-kinase from the cytosol in a concentration-dependent manner, indicating that sevoflurane is able to inhibit vasoconstriction mediated by the Rho/Rho-kinase pathway in rat aortic smooth muscle.