Single-channel and functional characteristics of a KCa channel in vascular muscle membranes of human saphenous veins.
Single-channel and functional characteristics of a KCa channel in vascular muscle membranes of human saphenous veins.
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人隐静脉血管肌膜 KCa 通道的单通道和功能特征。
DOI：
10.1097/00005344-199611000-00002
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发表时间：
1996
影响因子：
3
通讯作者：
Rusch,NJ
中科院分区：
文献类型：
--
作者：
Zhang,H;Li,P;Almassi,GH;Nicolosi,A;Olinger,GN;Rusch,NJ
隐静脉被广泛用于测试血管舒张物质对静脉反应性的影响，但介导血管舒张的K+通道类型尚未确定。因此，本研究的目标是确定人隐静脉（HSV）血管平滑肌膜中的K+通道类型，这可能有助于膜复极和静脉张力的控制。将从旁路手术获得的14个HSV酶促解离成单个血管肌细胞，用于由内而外的膜片的膜片钳分析（n= 81）。HSV膜主要显示高电导（226 pS）K+通道，在生理电压下占总膜片电流的≥ 95%。通道具有高的K+选择性，对Ca 2+和电压敏感，可被100 nM的伊比利亚毒素和≤ 1 mM的四乙基铵（TEA）阻断。这些Ca 2+敏感性通道（KCa）在暴露于300- 1，000 nM钙的去极化膜片中也显示出堆叠的开口，表明单个膜膜片中存在多个功能性KCa通道。在张力记录研究中，暴露于100 nM去甲肾上腺素的HSV分离片段在0.1-3 mM TEA对KCa通道进行性阻断期间进一步收缩，表明KCa通道是HSV平滑肌细胞复极和血管舒张的途径。我们发现的钾钙通道在平滑肌膜的HSV，如果扩展到其他人外周静脉的质膜，表明该通道可能代表一个治疗部位，用于缓解条件的静脉张力增加。
The saphenous vein is used extensively to test for the effects of vasodilator substances on venous reactivity, but the K+ channel types that mediate vasodilation have not been identified. Thus the goal of this study was to identify K+ channel types in vascular smooth muscle membranes of human saphenous vein (HSV), which may contribute to membrane repolarization and control of venous tone. Fourteen HSVs obtained from bypass surgery were enzymatically dissociated into single vascular myocytes for patch-clamp analysis of inside-out patches (n= 81). HSV membranes showed primarily high-conductance (226 pS) K+ channels, which accounted for≥ 95% of total patch current at physiologic voltages. Channels were highly K+ selective, showed steep voltage and Ca 2+ sensitivity, and were blocked by 100 nM iberiotoxin and≤ 1 mM tetraethlyammonium (TEA). These Ca 2+-sensitive channels (K Ca) also showed stacked openings in depolarized patches exposed to 300-1,000 nM calcium, suggesting multiple functional K Ca channels in a single membrane patch. In tension-recording studies, isolated segments of HSV exposed to 100 nM norepinephrine contracted further during progressive block of K Ca channels by 0.1-3 mM TEA, suggesting that K Ca channels are pathways for repolarization and vasodilation in HSV smooth muscle cells. Our finding of K Ca channels in smooth muscle membranes of HSV, if extended to the plasma membranes of other human peripheral veins, suggests that this channel may represent a therapeutic site for alleviation of conditions of increased venous tone.