Dominant role of an endothelium-derived hyperpolarizing factor (EDHF)-like vasodilator in the ciliary vascular bed of the bovine isolated perfused eye
作者:Alister J McNeish、William S Wilson、William Martin
DOI:10.1038/sj.bjp.0704332
日期:2001.10
The roles of the endothelium‐derived nitric oxide, prostacyclin and endothelium‐derived hyperpolarizing factor (EDHF) in mediating vasodilator responses to acetylcholine and bradykinin were assessed in the ciliary vascular bed of the bovine isolated perfused eye preparation.
Vasodilatation to acetylcholine or bradykinin was unaffected by the nitric oxide synthase inhibitor, L‐NAME (100 μM), or the cyclo‐oxygenase inhibitor, flurbiprofen (30 μM), but was virtually abolished following treatment with a high concentration of KCl (30 mM), or by damaging the endothelium with the detergent, CHAPS (0.3%, 2 min).
Acetylcholine‐induced vasodilatation was unaffected by glibenclamide (10 μM), an inhibitor of ATP‐sensitive K+ channels (K+ATP), but was significantly attenuated by TEA (10 mM), a non‐selective inhibitor of K+ channels.
The small conductance calcium‐sensitive K+ channel (SK+Ca) inhibitor, apamin (100 nM), and the large conductance calcium‐sensitive K+ channel (BK+Ca) inhibitor, iberiotoxin (50 nM), had no significant effect on acetylcholine‐induced vasodilatation. In contrast, the intermediate (IK+Ca)/large conductance calcium‐sensitive K+ channel inhibitor, charybdotoxin (50 nM), powerfully blocked these vasodilator responses, and uncovered a vasoconstrictor response.
The combination of apamin (100 nM) with a sub‐threshold concentration of charybdotoxin (10 nM) significantly attenuated acetylcholine‐induced vasodilatation, but the combination of apamin (100 nM) with iberiotoxin (50 nM) had no effect.
In conclusion, blockade by a high concentration of KCl, by charybdotoxin, or by the combination of apamin with a sub‐threshold concentration of charybdotoxin, strongly suggests that vasodilatation in the bovine isolated perfused eye is mediated by an EDHF.
British Journal of Pharmacology (2001) 134, 912–920; doi:10.1038/sj.bjp.0704332
以下是中文翻译:
评估了来自内皮的NO、前列环素和内皮源性超极化因子(EDHF)在介导乙酰胆碱和缓激肽引发的血管舒张反应中的作用,实验对象为牛孤立灌注眼的睫状血管床。
乙酰胆碱或缓激肽引起的血管舒张不受NO合成酶抑制剂(L-NAME,100 μM)或环氧化酶抑制剂(flurbiprofen,30 μM)的影响,但在给予高浓度KCl(30 mM)或使用洗涤剂CHAPS(0.3%,2 min)破坏内皮后,血管舒张几乎完全消失。
乙酰胆碱诱导的血管舒张不受ATP敏感型K+通道抑制剂(glibenclamide,10 μM)的影响,但在给予非选择性K+通道抑制剂(TEA,10 mM)后显著减弱。
小导电钙敏感型K+通道(SK+Ca)抑制剂(apamin,100 nM)和大导电钙敏感型K+通道(BK+Ca)抑制剂(iberiotoxin,50 nM)对乙酰胆碱诱导的血管舒张无显著影响。相比之下,中/大导电钙敏感型K+通道抑制剂(charybdotoxin,50 nM)强烈阻断了这些血管舒张反应,并揭示了血管收缩反应。
apamin(100 nM)与sub-threshold浓度的charybdotoxin(10 nM)组合显著减弱乙酰胆碱诱导的血管舒张,而apamin(100 nM)与iberiotoxin(50 nM)组合无影响。
综上所述,高浓度KCl、charybdotoxin或apamin与sub-threshold浓度charybdotoxin的组合对血管舒张的强烈阻断,强烈表明牛孤立灌注眼中的血管舒张是由EDHF介导的。
British Journal of Pharmacology (2001) 134, 912–920; doi:10.1038/sj.bjp.0704332