Chronic hypoxia increases intracellular Ca2+ concentration and augments proliferation by enhancing store-operated Ca2+ entry in pulmonary arterial smooth muscle cells / 中华内科杂志

ABSTRACT

Objective To determine whether store-operated Ca2+ entry (SOCE) is involved in chronic hypoxia-induced alteration of intracellular Ca2 + concentration ([Ca2+] i) and proliferation in pulmonary arterial smooth muscle cells (PASMC).Methods Rat PASMCs were cultured and treated in normoxia (21％O2) or hypoxia (4％ O2) condition.The proliferation of PASMC was detected by cell counting kit-8 (CCK-8) assay.[Ca2 +] i,SOCE and the effects of store-operated Ca2 + channel (SOCC) inhibitors,SKF96365 and NiCl2,on SOCE in hypoxic PASMCs were tested by InCyte [Ca2 +] i measurement system.Results Hypoxia for 24-60 h augmented PASMC proliferation (1.12 ± 0.09 vs 0.71 ± 0.05,P ＜ 0.05) and [Ca2 +] i [(214.8 ± 20.4) nmol/L vs (115.2 ± 13.2) nmol/L,P ＜ 0.05] in a time-dependent manner with the maximum effect at 60 h.Perfusion of Ca2+-free Krebs solution containing nifedipine (5 μ mol/L),cyclopiazonic acid (CPA,10 μmol/L) in PASMCs caused a small transient increase of [Ca2+]i with peak [Ca2+]i (113.3 ± 49.3) nmol/L.Chronic hypoxia (4％ O2,60 h) enhanced [Ca2+]i level with peak value of (193.2 ± 22.7) nmol/L (P ＜ 0.05) in PASMC.After restoration of extracellular Ca2+,CPA caused marked increase of [Ca2+]i with peak value of (328.0 ± 56.7) nmol/L.Chronic hypoxia strengthened CPA-induced increase of [Ca2 +] i with peak value of (526.0 ± 33.7) nmol/L (P ＜ 0.05) in PASMCs.Either SKF96365 50 μmol/L or NiCl2 500 μmol/L distinctly attenuated CPA-induced enhancement of [Ca2 +] i,the peak value of which dropped from (526.0 ± 33.7) nmol/L to (170.4 ± 26.4) nmol/L (P＜0.05) or (177.4±45.9) nmol/L (P＜0.05) respectively.Conclusion Chronic hypoxia boosts the release of Ca2+ from sarcoplasmic reticulum and promotes the activity of SOCC and SOCE,leading to [Ca2 +] i elevation and proliferation of rat PASMCs.