Hypoxia Selectively Upregulates Cation Channels and Increases Cytosolic [Ca2+] in Pulmonary, but not Coronary, Arterial Smooth Muscle Cells

Ca2+ signaling, particularly the mechanism via store-operated Ca2+ entry (SOCE) and receptor-operated Ca2+ entry (ROCE), plays a critical role in the development of acute hypoxia-induced pulmonary vasoconstriction and chronic hypoxia-induced pulmonary hypertension. This study aimed to test the hypothesis that chronic hypoxia differentially regulates the expression of proteins that mediate SOCE and ROCE (STIM, Orai, and TRPC6) in pulmonary (PASMC) and coronary (CASMC) artery smooth muscle cells. The resting cytosolic [Ca2+] ([Ca2+]cyt) and the stored [Ca2+] in the sarcoplasmic reticulum (SR) were not different in CASMC and PASMC. Seahorse measurement showed a similar level of mitochondrial bioenergetics (basal respiration and ATP production) between CASMC and PASMC. Glycolysis was significantly higher in PASMC than in CASMC. The amplitudes of CPA-induced SOCE and OAG-induced ROCE in CASMC are slightly, but significantly, greater than in PASMC. The frequency and the area under the curve of Ca2+ oscillations...