Effects of chronic hypoxia on intracellular calcium concentration in pulmonary arterial smooth muscle cells

AIM: To study the effect of chronic hypoxia(CH) on the intracellular calcium([Ca~(2+)]i) in pulmonary artery smooth muscle cells(PASMCs) and the role of L-type calcium channel and calcium store. METHODS: The rat chronic hypoxia model was set up and intervene the PASMCs with normal PSS,calcium-free PSS,nifedipine,and heparine respectively.The resting [Ca~(2+)]i was determined with the Fura-2/AM calcium imaging technique.RESULTS:(1) The [Ca~(2+)]i in CH group in normal PSS was higher than that in control group in normal PSS(P0.05).The([Ca~(2+)]i) in CH group in normal PSS was higher than that in calcium-free PSS(P0.05).(2) No obvious change of [Ca~(2+)]i before and after application of nifedipine in PASMCs of CH groups was observed.(3) No difference of [Ca~(2+)]i before and after application of heparine in PASMCs of CH groups was detected.CONCLUSION: Chronic hypoxia increased the [Ca~(2+)]i in PASMCs.Chronic hypoxia induced increase in([Ca~(2+)]i) may relate to the influx of extracellular calcium,but not due to the L-type calcium channel or the IP_3R modulation only.