H₂O₂ decreases ASIC1 plasma membrane localization in rat pulmonary arterial smooth muscle cells (1175.3)

Abstract

Acid sensing ion channel 1 (ASIC1) mediates enhanced store operated calcium entry (SOCE) in pulmonary arterial smooth muscle cells (PASMC) and contributes to the development of chronic hypoxia (CH)‐induced pulmonary hypertension. ASIC1 is a redox sensitive ion channel, such that reducing agents increase and oxidizing agents decrease channel activity. Recent studies from our laboratory have shown that 1) hydrogen peroxide (H2O2) inhibits ASIC1‐dependent SOCE in PASMC and 2) pulmonary arterial H2O2 levels are decreased following CH which may contribute to the enhanced SOCE. Considering that H2O2 has additionally been shown to decrease ASIC1 cell surface expression in neurons, we hypothesized that H2O2 inhibits plasma membrane localization of ASIC1 in PASMC. Using a cell surface biotinylation assay, we found a 2.9 ± 0.1 fold increase in plasma membrane ASIC1 expression in PASMC from CH animals compared to control (two‐tailed P value=0.0002). In PASMC from control rats pretreatment with PEG‐catalase (250 U/ml; 1 hr at 37°C) increased and H2O2 (25 µM; 1 hr at 37°C) decreased ASIC1 surface expression compared to vehicle treated PASMC (one way ANOVA P value<0.001). We conclude that ASIC1 plasma membrane localization is inhibited by H2O2 in PASMC and this represents one potential mechanism by which the loss of H2O2 following CH enhances ASIC1‐dependent Ca2+ influx in PASMC. Grant Funding Source: Supported by T32‐HL07736; R01‐HL111084; K01 HL092598