Benefit of combined therapy with nicorandil and colchicine in preventing monocrotaline-induced rat pulmonary arterial hypertension

This study tested the hypothesis that combined therapy with nicorandil and colchicine is superior to either alone in attenuating monocrotaline (MCT)-induced rat pulmonary arterial hypertension (PAH). Adult male Sprague-Dawley rats (n = 50) were equally randomized into group 1 (sham control), group 2 [MCT (60 mg/kg i.p.)], group 3 [MCT-Nicorandil (5.0 mg/kg/day)], group 4 [MCT-Colchicine (1.0 mg/kg/day)], and group 5 (MCT-Nicorandil-Colchicine). Drugs were given on day 5. All animals were sacrificed on day 90 after MCT administration. Right ventricular systolic blood pressure (RVSBP) and RV weight were increased in group 2 compared to group 1, reduced in groups 3 and 4 compared to group 2, and further reduced in group 5, whereas arterial-oxygen saturation showed an opposite pattern (all p < 0.001). Pulmonary damage severity (thickened alveolar septum and pulmonary arteriolar wall, decreased alveolar-sac numbers), number of CD3+ cells, and protein expressions of inflammatory (MMP-9, NF-κB, VCAM-1, angiotensin II-receptor), apoptotic (Bax, caspase 3, cleaved PARP), and fibrotic (TGF-β, Smad3) biomarkers showed an identical pattern compared to that of RVSBP, whereas pulmonary expressions of anti-apoptotic (Bcl-2) and anti-fibrotic (BMP-2, Smad1/5) biomarkers displayed a reverse pattern (all p < 0.01). The protein expressions of RV damage markers (BNP, caspase 3) were increased, whereas expression of biomarker for RV functional preservation (Cx43) was reduced in group 2 compared with group 1, elevated in groups 3 and 4 compared to group 2, and further increased in group 5 (all p < 0.01). Combined therapy with nicorandil and colchicine is superior to either alone in attenuating MCT-induced PAH in rats.