Preventive and Therapeutic Effects of Pimobendan in Rats with Monocrotaline-Induced Pulmonary Arterial Hypertension

Abstract

The aim of the present study was to investigate the therapeutic action of pimobendan in rats with monocrotaline (MCT)-induced pulmonary hypertension (PH). Twenty-four 12-week-old male Sprague-Dawley rats were injected with MCT or saline solution. They then received either no further treatment (MCT group) or oral pimobendan immediately (early-phase treatment) or 4 weeks (late-phase treatment) after injection. At day 42 after MCT injection, echocardiography was performed and then right ventricular systolic pressure was measured via a cardiac catheter. There were no differences in hemodynamic variables between the pimobendan-treated groups and the saline group, regardless of the timing of therapy. It was suggested that acrocinesis was caused by excess pimobendan in the early phase, whereas in the late phase during PH progression, pimobendan preserved diastolic function without an increase in HR.