Activation of rat mesenteric arterial KATP channels by 11,12-epoxyeicosatrienoic acid.
Activation of rat mesenteric arterial KATP channels by 11,12-epoxyeicosatrienoic acid.
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11,12-环氧二十碳三烯酸激活大鼠肠系膜动脉 KATP 通道。
DOI：
10.1152/ajpheart.00423.2004
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Lee,Hon-Chi
中科院分区：
文献类型：
--
作者：
Ye,Dan;Zhou,Wei;Lee,Hon-Chi
环氧二十碳三烯酸（Epoxyeicosatrienoicacids，ESTs）是花生四烯酸的细胞色素P-450表氧化酶代谢产物，是内皮源性超极化因子的候选者。我们以前曾报道过，内皮素是心脏ATP敏感性K+（KATP）通道的有效激活剂，但其对血管KATP通道的作用尚不清楚。使用全细胞膜片钳技术，在移液管中加入0.1 mM ATP并保持在−60 mV，从大鼠肠系膜动脉新鲜分离的平滑肌细胞在基线时具有较小的格列本脲敏感电流（13.1 ± 3.9 pA，n= 5），显示10 μM吡那地尔激活7.2倍（94.1 ± 21.9 pA，n= 7，P< 0.05）。11，12-EET剂量依赖性地激活KATP电流，表观EC 50为87 nM。在移液器溶液中加入PKA抑制剂肽（5 μM）可抑制500 nM 11，12-EET对KATP通道的激活，但加入PKC抑制剂肽（100 μM）则无抑制作用。血管反应性研究证实了这些结果。11，12-EET在离体肠系膜小动脉中产生剂量依赖性血管舒张，格列本脲（1 μM）预孵育可使该效应降低50%。通过与细胞渗透性PKA抑制剂肉豆蔻酰化PKI（14-22）预孵育，11，12-EET对血管舒张的作用也显著减弱，在PKA抑制剂存在的情况下，格列本脲没有额外的作用。这些结果表明，11，12-EET是一种有效的血管KATP通道激活剂，其作用依赖于PKA活性。
Epoxyeicosatrienoic acids (EETs), the cytochromeP-450 epoxygenase metabolites of arachidonic acid, are candidates of endothelium-derived hyperpolarizing factors. We have previously reported that EETs are potent activators of cardiac ATP-sensitive K+(KATP) channels, but their effects on the vascular KATPchannels are unknown. With the use of whole cell patch-clamp techniques with 0.1 mM ATP in the pipette and holding at −60 mV, freshly isolated smooth muscle cells from rat mesenteric arteries had small glibenclamide-sensitive currents at baseline (13.1 ± 3.9 pA,n= 5) that showed a 7.2-fold activation by 10 μM pinacidil (94.1 ± 21.9 pA,n= 7,P< 0.05). 11,12-EET dose dependently activated the KATPcurrent with an apparent EC50of 87 nM. Activation of the KATPchannels by 500 nM 11,12-EET was inhibited by inclusion of the PKA inhibitor peptide (5 μM) but not by the inclusion of the PKC inhibitor peptide (100 μM) in the pipette solution. These results were corroborated by vasoreactivity studies. 11,12-EET produced dose-dependent vasorelaxation in isolated small mesenteric arteries, and this effect was reduced by 50% with glibenclamide (1 μM) preincubation. The 11,12-EET effects on vasorelaxation were also significantly attenuated by preincubation with cell-permeant PKA inhibitor myristoylated PKI(14–22), and, in the presence of PKA inhibitor, glibenclamide had no additional effects. These results suggest that 11,12-EET is a potent activator of the vascular KATPchannels, and its effects are dependent on PKA activities.