Right ventricular overloading is attenuated in monocrotaline-induced pulmonary hypertension model rats with a disrupted Gpr143gene, the gene that encodes the 3,4-L-dihydroxyphenyalanine (L-DOPA) receptor

Pulmonary hypertension (PH) is a severe and progressive disease that causes elevated right ventricular systolic pressure, right ventricular hypertrophy and ultimately right heart failure. However, the underlying pathophysiologic mechanisms are poorly understood. We previously showed that 3,4-L-dihydroxylphenyalanine (DOPA) sensitizes vasomotor response to sympathetic tone via coupling between the adrenergic receptor alpha1 (ADRA1) and a G protein-coupled receptor 143 (GPR143), a DOPA receptor. We investigated whether DOPA similarly enhances ADRA1-mediated contraction in pulmonary arteries isolated from rats, and whether GPR143 is involved in the PH pathogenesis. Pretreating the isolated pulmonary arteries with DOPA 1 μM enhanced vasoconstriction in response to phenylephrine, an ADRA1 agonist, but not to U-46619, a thromboxane A2 agonist or endothelin-1. We generated Gpr143gene-deficient (Gpr143-/y) rats, and confirmed that DOPA did not augment phenylephrine-induced contractile response in Gpr143-/yrat pulmonary arteries. We generated a rat model of monocrotaline (MCT)-induced PH. In the MCT model, the right ventricular systolic pressure was attenuated in the Gpr143-/yrats than in WT rats. Phenylephrine-induced cell migration and proliferation were also suppressed in Gpr143-/ypulmonary artery smooth muscle cells than in WT cells. Our result suggests that GPR143 is involved in the PH pathogenesis in the rat models of PH.