Weir E K, Reeve H L, Cornfield D N, Tristani-Firouzi M, Peterson D A, Archer S L
Department of Medicine, VA Medical Center, Minneapolis, Minnesota, USA.
Kidney Int. 1997 Feb;51(2):462-6. doi: 10.1038/ki.1997.62.
Hypoxia causes pulmonary vasoconstriction (HPV), but also dilation of systemic vessels and the ductus arteriosus. In the adult animal. HPV is initiated by inhibition of potassium current (IK) in the smooth muscle cells of small resistance arteries, which results in membrane depolarization and calcium entry through voltage-gated calcium channels. The oxygen-sensitive channels that initiate HPV are 4-aminopyridine (4-AP)-sensitive delayed rectifier channels (KDR), the most prominent of which has a conductance of 37 pS. In the fetus, hypoxia causes pulmonary vasoconstriction through inhibition of a calcium-sensitive potassium channel (KCa). In smooth muscle cells from the rabbit ductus arteriosus, which dilates in response to hypoxia, whole-cell potassium current is reversibly enhanced, rather than inhibited, by hypoxia. The principal oxygen-sensitive channel is inhibited by 4-AP and has a conductance of about 58 pS. There are morphological and electrophysiological differences between individual pulmonary artery smooth muscle cells, for example, in some cells IK is predominantly carried by KDR channels and in others by KCa channels. KDR cells are more common in the resistance pulmonary arteries and KCa in the conduit arteries. Responses of specific vessels (conduit, resistance; pulmonary, systemic, ductus) at different stages of development (fetal, neonatal and adult) to changes in oxygen tension may be determined by the distribution of a variety of ion channels in the smooth muscle cells.
缺氧会导致肺血管收缩（HPV），但也会使体循环血管和动脉导管扩张。在成年动物中，HPV是由小阻力动脉平滑肌细胞中钾电流（IK）受到抑制引发的，这会导致膜去极化以及钙通过电压门控钙通道进入细胞。引发HPV的氧敏感通道是4 - 氨基吡啶（4 - AP）敏感的延迟整流通道（KDR），其中最主要的通道电导为37 pS。在胎儿中，缺氧通过抑制钙敏感钾通道（KCa）导致肺血管收缩。在兔动脉导管的平滑肌细胞中，该导管会对缺氧做出扩张反应，缺氧会使全细胞钾电流可逆性增强，而非受到抑制。主要的氧敏感通道受4 - AP抑制，电导约为58 pS。各个肺动脉平滑肌细胞之间存在形态学和电生理学差异，例如，在一些细胞中IK主要由KDR通道传导，而在另一些细胞中则由KCa通道传导。KDR细胞在肺阻力动脉中更为常见，而KCa细胞在肺导管动脉中更为常见。特定血管（导管、阻力血管；肺血管、体循环血管、动脉导管）在不同发育阶段（胎儿期、新生儿期和成年期）对氧张力变化的反应可能由平滑肌细胞中各种离子通道的分布所决定。
