Jackson W F
Department of Biological Sciences, College of Arts and Sciences, Western Michigan University, Kalamazoo 49008.
Am J Physiol. 1993 Nov;265(5 Pt 2):H1797-803. doi: 10.1152/ajpheart.1993.265.5.H1797.
The role of ATP-sensitive potassium channels (KATP) in determining resting arteriolar tone and vasodilator reactivity was assessed in superfused, hamster microcirculatory beds studied via intravital microscopy. Under resting conditions, the selective KATP blocker, glibenclamide, produced concentration-dependent vasoconstriction in both the cheek pouch and the cremaster muscle. Concentration-related constriction of cheek pouch arterioles was also observed with tetrapentylammonium, although this agent appeared to have toxic effects on the microcirculation. Glibenclamide (2 microM) abolished arteriolar vasodilation to cromakalim and pinacidil over a concentration range (10 nM-1 microM) in which these agents are selective KATP agonists and also significantly inhibited adenosine-, carbacyclin-, and isoproterenol-induced vasodilation. In contrast, responses to other vasodilators were not significantly affected [methacholine, forskolin, and dibutyryl adenosine 3',5'-cyclic monophosphate (cAMP)] or only slightly depressed (sodium nitroprusside). Thus the activity of KATP determines, in part, resting arteriolar tone in the hamster. Furthermore, vasodilators like adenosine, beta-adrenergic agonists, and prostacyclin appear to act through these ion channels by a mechanism that may not involve cAMP.
通过活体显微镜观察，在灌注的仓鼠微循环床中评估了ATP敏感性钾通道（KATP）在决定静息小动脉张力和血管舒张反应性方面的作用。在静息条件下，选择性KATP阻滞剂格列本脲在颊囊和提睾肌中均产生浓度依赖性血管收缩。虽然四戊铵对微循环似乎有毒性作用，但在颊囊小动脉中也观察到了与浓度相关的收缩。在浓度范围为10 nM - 1 μM（在此浓度范围内这些药物是选择性KATP激动剂）时，格列本脲（2 μM）消除了小动脉对克罗卡林和平卡地尔的血管舒张作用，并且还显著抑制了腺苷、卡前列环素和异丙肾上腺素诱导的血管舒张。相比之下，对其他血管舒张剂的反应没有受到显著影响[乙酰甲胆碱、福斯可林和二丁酰腺苷3',5'-环磷酸腺苷（cAMP）]或仅略有降低（硝普钠）。因此，KATP的活性部分决定了仓鼠的静息小动脉张力。此外，腺苷、β-肾上腺素能激动剂和前列环素等血管舒张剂似乎通过这些离子通道起作用，其机制可能不涉及cAMP。
