Background: Rho-kinase mediated vasoconstriction plays a key role in pulmonary hypertension (PH). We evaluated the acute effect of Rho-kinase inhibiter, Fasudil, on pulmonary artery input impedance (Z) in Sugen/Hypoxia rats. Method: We measured pulmonary artery pressure (PAP) and flow under irregular pacing and estimated Z in 3 weeks PH rats (n=6). Result: Fasudil significantly decreased PAP (50.5±6.4 vs 38.2±3.2 mmHg, p<0.01) and resistance (56.5±7.0 vs 39.9±5.2 mmHg/ml/sec, p<0.01), whereas increased compliance (1.82±0.4 vs 2.5±0.8 10-3×ml/mmHg, p<0.05). Conclusion: Rho-kinase inhibitor equally lowers the gain of Z regardless of frequency examined.
