PURPOSE: Angiotensin II (Ang II)-induced vasoconstriction is mediated by changes in intracellular free Ca(2+) concentration ([Ca(2+)](i)) and myofilament Ca(2+) sensitivity. Protein kinase C- and Rho kinase-mediated signaling pathways are proposed for the regulation of the Ca(2+) sensitization mechanisms. We have demonstrated that sevoflurane inhibits Rho kinase-mediated contraction of isolated rat aortic smooth muscle. A recent study demonstrated that Rho-kinase mediated Ca(2+) sensitization was involved in the pathophysiology of hypertension. This study was designed to investigate the effects of sevoflurane on Ang II-induced Rho kinase-mediated vascular contraction in spontaneously hypertensive rats (SHR). METHODS: The effects of sevoflurane on vasoconstriction, increase in [Ca(2+)](i), and membrane translocation of Rho kinase in response to Ang II were investigated in normotensive Wistar-Kyoto rats (WKY) and SHR, using an isometric force transducer, a fluorometer, and Western blotting, respectively. RESULTS: The inhibitory effects of sevoflurane on Ang II (10(-7)M)-induced contraction were greater (P < 0.05) in SHR than in WKY at the highest concentration of sevoflurane (5.1%). Y27632 (3 × 10(-7)M), a specific inhibitor of Rho kinase, inhibited the Ang II-induced contraction in SHR, but not in WKY. Sevoflurane did not affect the increases in [Ca(2+)](i) in response to Ang II in either strain. Ang II stimulated Rho kinase activity in SHR, which was almost abolished by sevoflurane at a concentration of 5.1% (P < 0.05). CONCLUSIONS: These findings suggest that the inhibition of the Ang II-induced contraction by sevoflurane in SHR may be, at least in part, due to the attenuation of the Rho kinase-mediated signaling pathway.
PURPOSE:Angiotensin II (Ang II)-induced vasoconstriction is mediated by changes in intracellular free Ca(2+) concentration ([Ca(2+)](i)) and myofilament Ca(2+) sensitivity. Protein kinase C- and Rho kinase-mediated signaling pathways are proposed for the regulation of the Ca(2+) sensitization mechanisms. We have demonstrated that sevoflurane inhibits Rho kinase-mediated contraction of isolated rat aortic smooth muscle. A recent study demonstrated that Rho-kinase mediated Ca(2+) sensitization was involved in the pathophysiology of hypertension. This study was designed to investigate the effects of sevoflurane on Ang II-induced Rho kinase-mediated vascular contraction in spontaneously hypertensiverats (SHR). METHODS: The effects of sevoflurane on vasoconstriction, increase in [Ca(2+)](i), and membrane translocation of Rho kinase in response to Ang II were investigated in normotensive Wistar-Kyoto rats (WKY) and SHR, using an isometric force transducer, a fluorometer, and Western blotting, respectively. RESULTS: The inhibitory effects of sevoflurane on Ang II (10(-7)M)-induced contraction were greater (P < 0.05) in SHR than in WKY at the highest concentration of sevoflurane (5.1%). Y27632 (3 × 10(-7)M), a specific inhibitor of Rho kinase, inhibited the Ang II-induced contraction in SHR, but not in WKY. Sevoflurane did not affect the increases in [Ca(2+)](i) in response to Ang II in either strain. Ang II stimulated Rho kinase activity in SHR, which was almost abolished by sevoflurane at a concentration of 5.1% (P < 0.05). CONCLUSIONS: These findings suggest that the inhibition of the Ang II-induced contraction by sevoflurane in SHR may be, at least in part, due to the attenuation of the Rho kinase-mediated signaling pathway.