[Change of voltage-gate potassium channel in pulmonary arterial smooth muscle cells of pulmonary hypertension induced by left-to-right shunt in rats].

OBJECTIVE: To investigate the electrophysiological changes of voltage-gate potassium channel (Kv) of pulmonary arterial smooth muscle cells of pulmonary arterial hypertension in rats induced by left to right shunt, and to analyze the role of Kv during the progress of pulmonary arterial hypertension. METHODS: Forty male SD rats were randomly divided into three groups, group A (control, n = 10), group B (sham operated only group, n = 10), and group C (PAH model group, n = 20). Mean pulmonary artery pressure (mPAP) and right ventricular hypertrophy index (RVHI) of each rat were measured, single pulmonary artery smooth muscle cell (PASMC) was obtained by acute enzyme separation method (collagenase I plus papain) and the conventional whole-cell patch clamp technique was used to record resting membrane potential (Em), potassium ion current of voltage-gated potassium channel, the I-V curve between each 2 groups was compared, and correlation of each parameter was analyzed. RESULT: (1) The mPAP and RVHI of group C were significantly higher than those of group A and group B (P < 0.01, respectively). (2) The Em of group C [(-33.00 ± 4.09) mV] was significantly higher than that of group A [(-48.10 ± 4.54) mV] and group B [(-51.11 ± 3.66) mV], P < 0.01. (3) The peak current at +50 mV of voltage-gated potassium channel: in group C [(64.80 ± 8.40) pA/pF], it was significantly lower than that of group A [(120.85 ± 11.66) pA/pF] and group B [(118.03 ± 10.18) pA/pF] (P < 0.01, respectively). None of the parameters showed any significant difference between group A and group B (P > 0.05 for all comparisons). (4) Compared with group A and group B, the I-V curve of group C significantly downward shifted (P < 0.01, respectively). The difference in I-V curve between group A and group B was not significant, P > 0.05. (5) The correlation of resting membrane potential and mPAP and RVHI had significantly positive correlation (P < 0.001, respectively); but the correlation of membrane current, membrane current density and mPAP, RVHI and resting membrane potential had significantly negative correlation (P < 0.001, respectively). CONCLUSION: During the formation process of left-to-right shunt induced pulmonary arterial hypertension, function of Kv channel was inhibited, suggesting that Kv channel may be the mechanism of pulmonary arterial hypertension induced by left-to-right shunting.