Enhanced relaxation to the Rho-kinase inhibitor Y-27632 in mesenteric arteries from mineralocorticoid hypertensive rats

Increased vasoconstriction is characteristic of hypertension. In this study , we tested the hypothesis that changes in vascular responses during minera locorticoid hypertension may be due to increased activation of the Rho/Rho- kinase pathway. To test this, relaxation responses to the Rho-kinase inhibi tor Y-27632 were determined by measuring isometric force in deendothelializ ed mesenteric arteries from mineralocorticoid-hypertensive rats and sham-op erated controls. Following agonist-induced contraction by serotonin (5-HT, 5-hydroxytryptamine), arteries from hypertensive rats demonstrated a greate r relaxation to the Rho-kinase inhibitor Y-27632 (65 +/- 5% vs. 28 +/- 10%) . Treatment with an EC50 concentration of Y-27632 following a KCI-induced c ontraction caused minimal relaxation of arteries in both groups of animals. These findings suggest that augmented Rho-kinase activity in the vasculatu re of mineralocorticoid hypertensive rats may contribute to the enhanced va scular reactivity of agonist-mediated stimuli characteristic of this model of hypertension. Copyright (C) 2001 S. Karger AG, Basel.