Fig. 1. Guanosine 5′-[γ-thio]triphosphate (GTPγS)–induced contractile response and the effect of Y27632 on the GTPγS-stimulated contraction of rat aortic endothelium-denuded rings. (A ) GTPγS (10−4m) elicited a sustained contraction that lasted at least 2 h. (B ) The highly specific Rho-kinase inhibitor Y27632 (3 × 10−6m) significantly inhibited GTPγS-developed contraction when applied after (A ) or 20 min before (B ) treatment with GTPγS. The recording was representative of eight independent experiments.