[Alternation of regulation system for pulmonary arterial tone in pulmonary hypertension].

In pulmonary artery smooth muscle cells(PASMC), the Ca-influx required for myogenic tone is mainly supplied through the L-type Ca channels, which sustained open around resting membrane potential. Therefore, the voltage-gated K channels, which determine membrane potential in PASMC, are critical for regulation of the Ca-influx and myogenic tone. The voltage-gated K channels are inhibited in hypoxic condition. The inhibition may be related to the hypoxic pulmonary vasoconstriction and the chronic hypoxia-induced pulmonary hypertension. In subjects with primary pulmonary hypertension, the voltage-gated K channels are also inhibited. On the other hand, the Ca-activated K channels of PASMC are also inhibited in chronic exposure with pulmonary hypertension. The reduction of the K channels in pulmonary hypertension may enhance proliferation of PASMC.