Bernardo N L, Okubo S, Maaieh M M, Wood M A, Kukreja R C
Division of Cardiology, Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
Am J Physiol. 1999 Jul;277(1):H128-35. doi: 10.1152/ajpheart.1999.277.1.H128.
The adenosine agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) induces delayed ischemic protection in vivo. We hypothesized that this protection is mediated by opening of ATP-sensitive K(+) (K(ATP)) channels and increased synthesis of 72-kDa heat shock protein (HSP 72). Six groups (n = 9-13 animals/group) of animals were studied: group I, control rabbits that received no treatment; group II, animals given glibenclamide (0.3 mg/kg iv) 30 min before ischemia; group III, animals given 5-hydroxydecanoate (5-HD; 5 mg/kg iv) 15 min before ischemia; group IV, rabbits treated with CCPA (0.1 mg/kg iv) 24 h before ischemia; and groups V and VI, CCPA-treated animals that received the K(ATP)-channel blockers glibenclamide or 5-HD, respectively, 30 or 15 min before ischemia. All animals were subjected to ischemia by 30 min of coronary artery occlusion followed by 3 h of reperfusion. Risk area was delineated by injection of 10% Evans blue dye, and infarct size was determined by triphenyltetrazolium staining. Action potential duration (APD) was measured with an epicardial electrode. HSP 72 was measured by Western blotting. CCPA caused a significant reduction in infarct size [12.02 +/- 1.0 vs. 40.0 +/- 3.8% (%area at risk) in controls, P < 0.01] that was blocked by glibenclamide (36.2 +/- 3.1%, P < 0.01) and 5-HD (35.0 +/- 2.9%, P < 0.01). Glibenclamide and 5-HD did not change infarct size in control rabbits. These blockers significantly suppressed ischemia-induced APD shortening in control and CCPA-treated animals. CCPA treatment did not induce HSP 72 in hearts. These data suggest that adenosine-initiated delayed protection is mediated via opening of K(ATP) channels but does not involve the synthesis of HSP 72.
腺苷激动剂2-氯-N(6)-环戊基腺苷(CCPA)可在体内诱导延迟性缺血保护。我们推测这种保护作用是通过ATP敏感性钾(K(ATP))通道的开放和72-kDa热休克蛋白(HSP 72)合成增加介导的。研究了六组动物（每组n = 9 - 13只）：第一组为未接受治疗的对照兔；第二组为在缺血前30分钟静脉注射格列本脲(0.3 mg/kg)的动物；第三组为在缺血前15分钟静脉注射5-羟基癸酸(5-HD；5 mg/kg)的动物；第四组为在缺血前24小时静脉注射CCPA(0.1 mg/kg)的兔；第五组和第六组分别为在缺血前30或15分钟接受K(ATP)通道阻滞剂格列本脲或5-HD治疗的CCPA处理动物。所有动物均通过冠状动脉闭塞30分钟，随后再灌注3小时进行缺血处理。通过注射10%伊文思蓝染料勾勒危险区域，并用三苯基四氮唑染色确定梗死面积。用体表电极测量动作电位时程(APD)。通过蛋白质印迹法测量HSP 72。CCPA使梗死面积显著减小[对照组为40.0±3.8%（危险区域面积百分比），CCPA组为12.02±1.0%，P < 0.01]，格列本脲(36.2±3.1%，P < 0.01)和5-HD(35.0±2.9%，P < 0.01)可阻断这种作用。格列本脲和5-HD对对照兔的梗死面积无影响。这些阻滞剂显著抑制了对照动物和CCPA处理动物缺血诱导的APD缩短。CCPA处理未诱导心脏中HSP 72的产生。这些数据表明，腺苷引发的延迟保护作用是通过K(ATP)通道的开放介导的，但不涉及HSP 72的合成。
