The Isoquinoline-Sulfonamide Compound H-1337 Attenuates SU5416/Hypoxia-Induced Pulmonary Arterial Hypertension in Rats

Pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure and right heart failure. Selective pulmonary vasodilators have improved the prognosis of PAH; however, they are not able to reverse pulmonary vascular remodeling. Therefore, a search for new treatment agents is required. H-1337 is an isoquinoline-sulfonamide compound that inhibits multiple serine/threonine kinases, including Rho-associated protein kinase (ROCK) and mammalian target of rapamycin (mTOR). Here, we investigated the effects of H-1337 on pulmonary hypertension and remodeling in the pulmonary vasculature and right ventricle in experimental PAH induced by SU5416 and hypoxia exposure. H-1337 and H-1337M1 exerted inhibitory effects on ROCK and Akt. H-1337 inhibited the phosphorylation of myosin light chain and mTOR and suppressed the proliferation of smooth muscle cells in vitro. H-1337 treatment also suppressed the phosphorylation of myosin light chain and mTOR in the pulmonary vasculature and decreased right ventricular systolic pressure and the extent of occlusive pulmonary vascular lesions. Furthermore, H-1337 suppressed aggravation of right ventricle hypertrophy. In conclusion, our data demonstrated that inhibition of ROCK and mTOR pathways with H-1337 suppressed the progression of pulmonary vascular remodeling, pulmonary hypertension, and right ventricular remodeling.