TRPC6, a therapeutic target for pulmonary hypertension

Am J Physiol Lung Cell Mol Physiol. 2021 Dec 1;321(6):L1161-L1182. doi: 10.1152/ajplung.00159.2021. Epub 2021 Oct 27.


Idiopathic pulmonary arterial hypertension (PAH) is a fatal and progressive disease. Sustained vasoconstriction due to pulmonary arterial smooth muscle cell (PASMC) contraction and concentric arterial remodeling due partially to PASMC proliferation are the major causes for increased pulmonary vascular resistance and increased pulmonary arterial pressure in patients with precapillary pulmonary hypertension (PH) including PAH and PH due to respiratory diseases or hypoxemia. We and others observed upregulation of TRPC6 channels in PASMCs from patients with PAH. A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) in PASMC triggers PASMC contraction and vasoconstriction, while Ca2+-dependent activation of PI3K/AKT/mTOR pathway is a pivotal signaling cascade for cell proliferation and gene expression. Despite evidence supporting a pathological role of TRPC6, no selective and orally bioavailable TRPC6 antagonist has yet been developed and tested for treatment of PAH or PH. In this study, we sought to investigate whether block of receptor-operated Ca2+ channels using a nonselective blocker of cation channels, 2-aminoethyl diphenylborinate (2-APB, administered intraperitoneally) and a selective blocker of TRPC6, BI-749327 (administered orally) can reverse established PH in mice. The results from the study show that intrapulmonary application of 2-APB (40 µM) or BI-749327 (3-10 µM) significantly and reversibly inhibited acute alveolar hypoxia-induced pulmonary vasoconstriction. Intraperitoneal injection of 2-APB (1 mg/kg per day) significantly attenuated the development of PH and partially reversed established PH in mice. Oral gavage of BI-749327 (30 mg/kg, every day, for 2 wk) reversed established PH by ∼50% via regression of pulmonary vascular remodeling. Furthermore, 2-APB and BI-749327 both significantly inhibited PDGF- and serum-mediated phosphorylation of AKT and mTOR in PASMC. In summary, the receptor-operated and mechanosensitive TRPC6 channel is a good target for developing novel treatment for PAH/PH. BI-749327, a selective TRPC6 blocker, is potentially a novel and effective drug for treating PAH and PH due to respiratory diseases or hypoxemia.

Keywords: BI-749327; calcium signaling; hypoxic pulmonary vasoconstriction; pulmonary hypertension; transient receptor potential channel.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Boron Compounds / pharmacology
  • Calcium Signaling
  • Cells, Cultured
  • Gene Expression Regulation / drug effects*
  • Humans
  • Hypertension, Pulmonary / drug therapy
  • Hypertension, Pulmonary / metabolism
  • Hypertension, Pulmonary / pathology*
  • Mice
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism
  • Muscle, Smooth, Vascular / pathology*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Pulmonary Artery / drug effects
  • Pulmonary Artery / metabolism
  • Pulmonary Artery / pathology*
  • TOR Serine-Threonine Kinases / genetics
  • TOR Serine-Threonine Kinases / metabolism
  • TRPC6 Cation Channel / antagonists & inhibitors
  • TRPC6 Cation Channel / genetics
  • TRPC6 Cation Channel / metabolism*
  • Vasoconstriction*


  • Boron Compounds
  • TRPC6 Cation Channel
  • TRPC6 protein, human
  • Trpc6 protein, mouse
  • 2-aminoethoxydiphenyl borate
  • TOR Serine-Threonine Kinases