Decrease of extracellular pH modulates the whole cell voltage-gated potassium currents in rat pulmonary artery smooth muscle cells / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To study the modulation of extracellular pH on the voltage-gated potassium currents (I(Kv)) in isolated pulmonary artery smooth muscle cells (PASMCs).</p><p><b>METHODS</b>I(Kv) was recorded using whole-cell patch clamp technique under the external solutions with different pH. The electrophysiological characteristics of I(Kv) were then analyzed.</p><p><b>RESULTS</b>(1) As compared to the normoxic group, I(K), decreased under acidic condition. When the extracellular pH were 7.0, 6.5, 6.0, the peak currents at a potential of +60 mV were inhibited by 16.93% +/- 2.47% (P < 0.01), 33.03% +/- 2.13% (P < 0.01), 41.59% +/- 6.53% (P < 0.01) respectively, and the current-voltage relationship (I/V) curve shifted to the right. (2) When the extracellular pH was 7.0, 6.5, 6.0, the voltage-depended Gk-Em was shifted to the direction of positive and the activation was sped up.</p><p><b>CONCLUSION</b>The results suggest that with the development of hypoxic pulmonary vasoconstriction (HPV), extracellular pH may take part in the modulation of Kv channels partly, then make the cell depolarized and decrease the Kv currents, this will lead to open the L-type calcium channel and contract the pulmonary artery smooth muscle. It may be one of the mechanisms that hypoxic leads to HPV and finally accelerate the development of HPV.</p>