Rho kinase and Na+/H+ exchanger mediate endothelin‐1‐induced pulmonary arterial smooth muscle cell proliferation and migration

• Published in: Physiological reports 2018-05, Vol.6 (9), p.e13698-n/a
• Main Authors: Huetsch, John C., Walker, Jasmine, Undem, Clark, Lade, Julie, Yun, Xin, Baksh, Syeda, Jiang, Haiyang, Lai, Ning, Shimoda, Larissa A.
• Format: Article
• Language: English
• Subjects: Animals; Blood Pressure; Cell adhesion & migration; Cell migration; Cell Movement - drug effects; Cell proliferation; Cell Proliferation - drug effects; Endothelin; Endothelin-1 - administration & dosage; Endothelin-1 - metabolism; Endothelins; Homeostasis; Hydrogen; Hydrogen-Ion Concentration; Hypertension; Male; Membrane Physiology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Na+/H+-exchanging ATPase; Original Research; Physiology; Primary Cell Culture; pulmonary arterial smooth muscle; Pulmonary arteries; Pulmonary artery; Pulmonary Artery - drug effects; Pulmonary Artery - metabolism; Pulmonary hypertension; Rats, Wistar; Respiratory Conditions Disorder and Diseases; Rho kinase; Rho-associated kinase; rho-Associated Kinases - metabolism; Rodents; Smooth Muscle; Sodium-Hydrogen Exchangers - metabolism; sodium‐hydrogen exchanger
• ISSN: 2051-817X
• DOI: 10.14814/phy2.13698

Excessive production of endothelin‐1 (ET‐1) has been observed in almost all forms of pulmonary hypertension. ET‐1, a highly potent vasoconstrictor, can also potentiate pulmonary arterial smooth muscle cell (PASMC) growth and migration, both of which contribute to the vascular remodeling that occurs during the development of pulmonary hypertension. Increasing evidence indicates that alkalinization of intracellular pH (pHi), typically due to activation of Na+/H+ exchange (NHE), is associated with enhanced PASMC proliferation and migration. We recently demonstrated that application of exogenous ET‐1 increased NHE activity in murine PASMCs via a mechanism requiring Rho kinase (ROCK). However, whether ROCK and/or increased NHE activity mediate ET‐1‐induced migration and proliferation in PASMCs remains unknown. In this study, we used fluorescent microscopy in transiently cultured PASMCs from distal pulmonary arteries of the rat and the pH‐sensitive dye, BCECF‐AM, to measure changes in resting pHi and NHE activity induced by exposure to exogenous ET‐1 (10−8 mol/L) for 24 h. Cell migration and proliferation in response to ET‐1 were also measured using Transwell assays and BrdU incorporation, respectively. We found that application of exogenous ET‐1 had no effect on NHE1 expression, but increased pHi, NHE activity, migration, and proliferation in rat PASMCs. Pharmacologic inhibition of NHE or ROCK prevented the ET‐1‐induced changes in cell function (proliferation and migration). Our results indicate that ET‐1 modulates PASMC migration and proliferation via changes in pHi homeostasis through a pathway involving ROCK. Endothelin‐1 increased resting pH and sodium‐hydrogen exchange (NHE) activity in rat pulmonary arterial smooth muscle cells (PASMCs). Endothelin‐1 also increased PASMC proliferation and migration and these changes in PASMC function were dependent on NHE and Rho kinase activation.