Constriction of retinal arterioles to endothelin-1: requisite role of rho kinase independent of protein kinase C and L-type calcium channels.
Constriction of retinal arterioles to endothelin-1: requisite role of rho kinase independent of protein kinase C and L-type calcium channels.
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DOI：
10.1167/iovs.12-9542
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发表时间：
2012-05
影响因子：
4.4
通讯作者：
Luke B. Potts;Yi Ren;Guangrong Lu;Enoch Kuo;Ellen Ngo;L. Kuo;T. Hein
中科院分区：
文献类型：
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作者：
Luke B. Potts;Yi Ren;Guangrong Lu;Enoch Kuo;Ellen Ngo;L. Kuo;T. Hein
目的内皮素-1(ET-1)是一种强烈的血管收缩多肽，与多种视网膜病变有关，但血管收缩的潜在机制尚不完全清楚。我们通过评估细胞外钙(Ca²⁺)、L型电压调节钙通道(L-VOCCs)、Rho激酶(ROCK)和蛋白激酶C(PKC)在ET-1诱导的猪视网膜小动脉收缩中的作用来解决这个问题，所有这些都与血管平滑肌收缩有关。方法分离猪视网膜小动脉(~5 0~10 0μm)，用于血管运动研究和ROCK亚型的分子鉴定。结果在55cmH₂O压力下，离体小动脉基础张力稳定，收缩至ET-1(0.1nM)，20min内静息内径缩小40±6%。在没有腔外钙⁺的情况下，小动脉失去了基础张力，不能收缩到ET-1。尽管L-血管紧张素转换酶抑制剂硝苯地平降低基础张力，阻断对蛋白激酶C激动剂PDBu的收缩作用，但对ET-1的收缩作用不受影响。广谱PKC抑制剂Gö-6983可阻断对PDBu的血管收缩作用，但不改变ET-1引起的血管收缩或基础张力。用岩石抑制剂H-1152孵育小动脉可消除对ET-1和PDBu的基础张力和血管收缩。ROCK1和ROCK2亚型在视网膜小动脉壁均有表达。结论经L血管内皮细胞的细胞外钙离子内流和基底岩活性在维持猪视网膜小动脉的基础色调中起重要作用。ET-1的收缩作用不依赖于L血管内皮细胞，而是由细胞外钙离子内流和ROCK激活所介导，而不依赖于⁺。然而，直接激活PKC可以通过L-VOCC和ROCK信号引起血管收缩。
PURPOSE Although endothelin-1 (ET-1) is a potent vasoconstrictor peptide implicated in several retinal pathologies, the underlying mechanism of vasoconstriction is understood incompletely. We addressed this issue by assessing the contributions of extracellular calcium (Ca²⁺), L-type voltage-operated calcium channels (L-VOCCs), Rho kinase (ROCK), and protein kinase C (PKC) to ET-1-induced constriction of porcine retinal arterioles, all of which have been implicated commonly in vascular smooth muscle contraction. METHODS Porcine retinal arterioles (~50-100 μm) were isolated for vasomotor study and molecular assessment of ROCK isoforms. RESULTS Isolated arterioles developed stable basal tone at 55 cmH₂O luminal pressure and constricted to ET-1 (0.1 nM) with a 40 ± 6% reduction in resting diameter in 20 minutes. In the absence of extraluminal Ca²⁺, arterioles lost basal tone and failed to constrict to ET-1. Although L-VOCC inhibitor nifedipine reduced basal tone and blocked vasoconstriction to PKC activator PDBu, vasoconstriction to ET-1 was unaffected. The broad-spectrum PKC inhibitor Gö-6983 abolished vasoconstriction to PDBu, but did not alter ET-1-induced vasoconstriction or basal tone. Incubation of arterioles with ROCK inhibitor H-1152 abolished basal tone and vasoconstrictions to ET-1 and PDBu. Both ROCK1 and ROCK2 isoforms were expressed in the retinal arteriolar wall. CONCLUSIONS Extracellular Ca²⁺ entry via L-VOCCs and basal ROCK activity play important roles in the maintenance of basal tones of porcine retinal arterioles. ET-1-induced constriction is mediated by extracellular Ca²⁺ entry independent of L-VOCCs and by ROCK activation without the involvement of PKC. However, direct PKC activation can cause vasoconstriction via L-VOCC and ROCK signaling.