Circulation research
-
Circulation research · Sep 2004
Chronic hypoxia-induced upregulation of store-operated and receptor-operated Ca2+ channels in pulmonary arterial smooth muscle cells: a novel mechanism of hypoxic pulmonary hypertension.
Chronic hypoxic pulmonary hypertension is associated with profound vascular remodeling and alterations in Ca(2+) homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Recent studies show that transient receptor potential (TRPC) genes, which encode store-operated and receptor-operated cation channels, play important roles in Ca(2+) regulation and cell proliferation. However, the influence of chronic hypoxia on TRPC channels has not been determined. ⋯ They were accompanied by significant increases in basal, OAG-induced, and thapsigargin-induced cation entries in hypoxic PASMCs. Moreover, removal of Ca(2+) or inhibition of store-operated Ca(2+) entry with La(3+) and SK&F-96365 reversed the elevated basal [Ca(2+)](i) in PASMCs and vascular tone in PAs of chronic hypoxic animals, but nifedipine had minimal effects. Our results for the first time to our knowledge show that both store- and receptor-operated channels of PASMCs are upregulated by chronic hypoxia and contribute to the enhanced vascular tone in hypoxic pulmonary hypertension.