Changes of Rho kinase activity after hemorrhagic shock and its role in shock-induced biphasic response of vascular reactivity and calcium sensitivity.
ABSTRACT The purpose of the present study is to investigate the changes of Rho kinase activity and its role in biphasic response of vascular reactivity and calcium sensitivity after hemorrhagic shock. The vascular reactivity and calcium sensitivity of superior mesenteric artery (SMA) from hemorrhagic shock rats were determined via observing the contraction initiated by norepinephrine (NE) and Ca under depolarizing conditions (120 mmol/L K) with isolated organ perfusion system. At same time, Rho kinase activity in mesenteric artery was measured, and the effects of Rho kinase activity-regulating agents, angiotensin II (Ang-II), insulin, and Y-27632, on vascular reactivity and calcium sensitivity were also observed. The results indicated that the vascular reactivity and calcium sensitivity were increased at early shock (immediate and 30 min after shock) and decreased at late shock (1 and 2 h after shock). The maximal contractions of NE and Ca were significantly increased (P < 0.05 or P < 0.01) at early shock. But they were significantly decreased at late shock (P < 0.05 or P < 0.01). Rho kinase activity was significantly increased at early shock (immediate after shock) (P < 0.05) but significantly decreased at 1 and 2 h after shock (P < 0.05 or P < 0.01). It was positively correlated with the changes of vascular reactivity and calcium sensitivity. Insulin decreased the increased contractile response of SMA to NE and Caat early shock (P < 0.05 or P < 0.01). Angiotensin II increased the decreased contractile response of SMA to NE and Ca at 2-h shock (P < 0.05 or P < 0.01); Y-27632, Rho kinase-specific antagonist, decreased the contractile response of SMA to NE and Ca at 2-h shock, and abolished Ang-II induced the increase of vascular reactivity and calcium sensitivity. The results suggest that Rho kinase may be involved in the biphasic change of vascular reactivity and calcium sensitivity after hemorrhagic shock. Rho kinase may regulate vascular reactivity through the regulation of calcium sensitivity. Rho kinase-regulating agents may have some beneficial effects on shock-induced vascular hyporeactivity.
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ABSTRACT: Our previous study showed that the ischemic preconditioning and pretreatment of adenosine triphosphate-sensitive potassium channel (KATP) opener, pinacidil, may induce a good protective effect on shock-induced vascular hyporeactivity. Whether the pretreatment of opener/activator of the large-conductance calcium-activated potassium channel (Bkca), NS1619, can also induce a protective effect on vascular reactivity and play a beneficial effect on subsequent hemorrhagic shock is not clear. With Sprague-Dawley rats subjected to hemorrhagic shock and their isolated superior mesenteric artery, the protective effect of NS1619 (0.5, 1, 2, and 4 mg/kg) pretreatment (30 minutes before hemorrhage shock) on vascular reactivity and the underlying mechanisms were observed. NS1619 pretreatment significantly improved the 72-hour survival of hemorrhagic shock rats, alleviated shock-induced decrease of vascular reactivity and calcium sensitivity, and increased the cardiac output and oxygen delivery. NS1619 2 mg/kg had the best effect. These protective effects of NS1619 pretreatment on vascular reactivity and calcium sensitivity were antagonized by RhoA inhibitor, C3 transferase, and Rho kinase antagonist, Y-27632. NS1619 pretreatment up-regulated the activities of RhoA, Rho-kinase, and PDZ-Rho GEF (guanine nucleotide exchange factor). These effects of NS1619 pretreatment were eliminated by RhoA inhibitor, C3 transferase. Bkca opener, NS1619 pretreatment has good protective effect on vascular reactivity and calcium sensitivity, which plays a good beneficial effect on hemorrhagic shock. The mechanism may be mainly through PDZ-Rho GEF-RhoA-Rho kinase pathway. Bkca channel may be a potential target for the treatment of shock-induced vascular hyporeactivity.The journal of trauma and acute care surgery. 01/2014;
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ABSTRACT: Our previous study demonstrated that Rho kinase and protein kinase C (PKC) played important parts in the regulation of vascular reactivity after shock. Using superior mesenteric arteries (SMAs) from hemorrhagic shock rats, and hypoxia-treated vascular smooth muscle cells (VSMCs), relationship of protein kinase C ε (PKC ε) regulation of vascular reactivity to Rho kinase as well as the signal transduction after shock, were investigated. The results showed that inhibition of Rho kinase with the Rho kinase-specific inhibitor Y-27632 antagonized the PKC ε-specific agonist carbachol and highly expressed PKC ε-induced increase of vascular reactivity in SMAs and VSMCs, whereas inhibition of PKC ε with its specific inhibitory peptide did not antagonize the Rho kinase agonist (U-46619)-induced increase of vascular reactivity in SMAs and VSMCs. Activation of PKC ε or highly expressed PKC ε upregulated the activity of Rho kianse and the phosphorylation of PKC-dependent phosphatase inhibitor-17 (CPI-17), zipper kinase (ZIPK), and integrin-linked kinase (ILK), whereas activation of Rho kinase only increased CPI-17 phosphorylation. The specific neutralization antibodies of ZIPK and ILK antagonized PKC ε-induced increases in the activity of Rho kinase, but CPI-17 neutralization antibody did not antagonize this effect. These results suggested that Rho kinase takes part in the regulation of PKC ε on vascular reactivity after shock. Rho kinase is downstream of PKC ε. PKC ε activates Rho kinase via ZIPK and ILK; CPI-17 is downstream of Rho kinase.Shock (Augusta, Ga.) 05/2014; · 2.87 Impact Factor