A role for receptor-operated Ca2+ entry in human pulmonary artery smooth muscle cells in response to hypoxia

作者：Chengchun Tang, W.K. Lim To, Fanwei Meng, Y Wang, Yuchun Gu · 发表于：Physiological Research · 年份：2010 · DOI：10.33549/physiolres.931875 · 被引用次数：35 · 研究领域：Ion Channels and Receptors、Ion channel regulation and function、Neuroscience of respiration and sleep

Hypoxic pulmonary vasoconstriction (HPV) is an important homeostatic mechanism in which increases of [Ca2+]i are primary events. In this study, primary cultured, human pulmonary artery smooth muscle cells (hPASMC) were used to examine the role of TRPC channels in mediating [Ca2+]i elevations during hypoxia. Hypoxia (PO2) about 20 mm Hg) evoked a transient [Ca2+]i elevation that was reduced by removal of extracellular calcium. Nifedipine and verapamil, blockers of voltage-gated calcium channels (VGCCs), attenuated the hypoxia-induced [Ca2+)]i elevation by about 30%, suggesting the presence of alternate Ca2+ entry pathways. Expression of TRPC1 and TRPC6 in hPASMC were found by RT-PCR and confirmed by Western blot analysis. Antagonists for TRPC, 2APB and SKF96365, significantly reduced hypoxia-induced [Ca2+]i elevation by almost 60%. Both TRPC6 and TRPC1 were knocked down by siRNA, the loss of TRPC6 decreased hypoxic response down to 21% of control, whereas the knockdown of TRPC1 reduced the hypoxia response to 85%, suggesting that TRPC6 might play a central role in mediating hypoxia response in hPASMC. However, blockade of PLC pathway caused only small inhibition of the hypoxia response. In contrast, AICAR, the agonist of AMP-activated kinase (AMPK), induced a gradual [Ca2+]i elevation, whereas compound C, an antagonist of AMPK, almost abolished the hypoxia response. However, co-immunoprecipitation revealed that AMPKalpha was not colocalized with TRPC6. Our data supports a role...