YS-49 is a novel positive inotropic isoquinoline compound. YS-49 has potential as a therapeutic strategy for the pathogenesis of Ang II-related vascular diseases such as hypertension and atherosclerosis, via the induction of HO-1 gene activity. YS-49 induced HO-1 protein production in a dose-and time-dependent manner in VSMCs. Treatment with YS-49 significantly and dose-dependently inhibited Ang II-induced VSMC proliferation, ROS production, and phosphorylation of JNK, but not P38 MAP kinase or ERK1/2.YS-49(32.8 microM) exhibited much stronger inhibitory effects on TXA(2) formation. The higher inhibitory potencies of YS-49 (IC(50): 3.3microM) than higenamine (IC(50): 140 microM) on AA induced rat platelet aggregation was presumed to be the result of low inhibitory effect of higenamine than YS-49 on TXA(2) production from AA. The oral administration of YS-49 (50 mg/kg) increased the recovery rates from the acute thrombotic challenge in mice and lowered the weight of thr