Acid Sensing Ion Channel 1 Contributes to Hypoxia‐Induced Proliferation and Hypertrophy in Mouse Pulmonary Arterial Smooth Muscle Cells

Abstract

Pulmonary hypertension is a common complication of chronic obstructive pulmonary disease (COPD) and results from vasoconstriction and pulmonary arterial remodeling. Our laboratory has shown that acid sensing ion channel 1 (ASIC1) contributes to the arterial remodeling associated with chronic hypoxia‐induced pulmonary hypertension. However, the specific role of ASIC1 in hypoxia‐induced migration, proliferation and hypertrophy of pulmonary arterial smooth muscle cells (PASMC) is currently unknown. We hypothesize that ASIC1 contributes to PASMC proliferation and hypoxia‐induced hypertrophy. To determine involvement of ASIC1 in proliferation, PASMC from wildtype (ASIC1+/+) and ASIC1 knockout (ASIC1−/−) mice were incubated with bromodeoxyuridine (BrdU; 10 μM) for 24, 48, and 72 hrs. PASMC were fixed and labeled with a conjugated Anti‐BrdU FITC antibody to measure BrdU incorporation in newly synthesized DNA by flow cytometric analysis. At 24, 48, and 72 hrs, the total amount of BrdU incorporation was increased in PASMC from ASIC1+/+ mice compared to PASMC from ASIC1−/− mice. To determine the contribution of ASIC1 to hypoxia‐induced hypertrophy, PASMC from ASIC1+/+ and ASIC1−/− mice were exposed to normoxia (21% O2, 5% CO2) or hypoxia (2–4% O2, 5% CO2) for 24, 48, or 72 hrs. Unlabeled fixed cells were processed by flow cytometry using the forward scatter parameter to determine cell size. Exposure to hypoxia increased PASMC size in both groups, however the hypertrophic response was greater in PASMC from ASIC1+/+ mice compared to PASMC from ASIC1−/− mice at 24, 48, and 72 hrs. These data demonstrate that ASIC1 contributes to proliferation and hypoxia‐induced hypertrophy of PASMC and provides an understanding of the mechanism(s) by which ASIC1 contributes to pulmonary arterial remodeling associated with chronic hypoxia‐induced pulmonary hypertension.Support or Funding InformationThis work was supported by National Heart, Lung, and Blood Institute Grants HL‐92598 (to N. L. Jernigan), HL‐111084 (to N. L. Jernigan), and the American Physiological Society STRIDE program (R25 HL115473)