Dysfunctional Voltage-Gated K+ Channels in Pulmonary Artery Smooth Muscle Cells of Patients With Primary Pulmonary Hypertension

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Abstract

Background

Primary pulmonary hypertension (PPH) is a rare disease of unknown cause. Although PPH and secondary pulmonary hypertension (SPH) share many clinical and pathological characteristics, their origins may be disparate. In pulmonary artery smooth muscle cells (PASMCs), the activity of voltage-gated K+ (KV) channels governs membrane potential (Em) and regulates cytosolic free Ca2+ concentration ([Ca2+]cyt). A rise in [Ca2+]cyt is a trigger of vasoconstriction and a stimulus of smooth muscle proliferation.

Conclusions

These results indicate that KV channel function in PPH-PASMCs is inhibited compared with SPH-PASMCs. The resulting membrane depolarization and increase in [Ca2+]cyt lead to pulmonary vasoconstriction and PASMC proliferation. Our data suggest that defects in PASMC KV channels in PPH patients may be a unique mechanism involved in initiating and maintaining pulmonary vasoconstriction and appear to play a role in the pathogenesis of PPH. (Circulation. 1998;98:1400-1406.)

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