Roles Of Calcium-activated Potassium Channel And ATP-sensitive Potassium Channel In Hypoxia-induced Pulmonary Vasoconstriction

The semi-quantitative RT-PCR test and Western blot were used to investigate the effect of hypoxia on the gene expression and protein level of large-conductance calcium-activated potassium channel ( BKCa ) and ATP-sensitive potassium channel(KATP) Kir6.1 and SUR2B in the cultured pulmonary artery smooth muscle cells (PASMCs).The results showed (1) BKCa and Kir6.1 and SUR2B encoding genes and proteins were expressed in cultured PASMCs of rats. (2) The gene and protein expressions of BKCa and Kir6.1 and SUR2B in PASMCs could be up-regulated by acute exposure to hypoxia for 6 hours. When cultured PASMCs were exposed to hypoxia for 48 hours, the gene and protein expressions of BKCa increased and the same happened to Kir6.1 when cultured PASMCs were exposed to hypoxia for 72 hours. (3) When cultured PASMCs were acutely exposed to hypoxia again after chronic treatment with hypoxia, the gene and protein expressions of BKCa and Kir6.1 and SUR2B had no significantly change compared with normal group. The results suggested that (1) The gene and protein expressions of BKCa and Kir6.1 and SUR2B channels in PASMCs could be up-regulated on condition of different times of hypoxia, which suggests at molecular level that BKCa and KATP may play a negative regulation role in hypoxic pulmonary vasoconstriction (HPV) and decrease the degree of HPV. (2) The result (3) may be one mechanism of the body adaptability to hypoxia.