Centre de Résonance Magnétique Biologique et Médicale, UMR CNRS n°6612, Faculté de Médecine de Marseille, Université de Méditerranée, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France.
Am J Physiol Heart Circ Physiol. 2010 Nov;299(5):H1679-86. doi: 10.1152/ajpheart.00998.2009. Epub 2010 Aug 20.
We investigated the tolerance of the insulin-resistant diabetic heart to ischemic injury in the male Goto-Kakizaki (GK) rat, a model of type 2 diabetes. Changes in energy metabolism, nitric oxide (NO) pathway, and cardiac function were assessed in the presence of physiological substrates. Age-matched control Wistar (n = 19) and GK (n = 18) isolated rat hearts were perfused with 0.4 mM palmitate, 3% albumin, 11 mM glucose, 3 U/l insulin, 0.2 mM pyruvate, and 0.8 mM lactate for 24 min before switching to 1.2 mM palmitate (11 rats/group) during 32 min low-flow (0.5 ml·min(-1)·g wet wt(-1)) ischemia. Next, flow was restored with 0.4 mM palmitate buffer for 32 min. A subset of hearts from each group (n = 8 for control and n = 7 for GK groups) were freeze-clamped for determining baseline values after the initial perfusion of 24 min. ATP, phosphocreatine (PCr), and intracellular pH (pH(i)) were followed using (31)P magnetic resonance spectroscopy with simultaneous measurement of contractile function. The NO pathway was determined by nitric oxide synthase (NOS) isoform expression and total nitrate concentration (NOx) in hearts. We found that coronary flow was 26% lower (P < 0.05) during baseline conditions and 61% lower (P < 0.05) during reperfusion in GK vs. control rat hearts. Rate pressure product was lower during reperfusion in GK vs. control rat hearts (P < 0.05). ATP, PCr, and pH(i) during ischemia-reperfusion were similar in both groups. Endothelial NOS expression was increased in GK rat hearts during baseline conditions (P < 0.05). NOx was increased during baseline conditions (P < 0.05) and after reperfusion (P < 0.05) in GK rat hearts. We report increased susceptibility of type 2 diabetic GK rat heart to ischemic injury that is not associated with impaired energy metabolism. Reduced coronary flow, upregulation of eNOS expression, and increased total NOx levels confirm NO pathway modifications in this model, presumably related to increased oxidative stress. Modifications in the NO pathway may play a major role in ischemia-reperfusion injury of the type 2 diabetic GK rat heart.
我们研究了胰岛素抵抗型糖尿病心脏对雄性 Goto-Kakizaki（GK）大鼠缺血性损伤的耐受性，GK 大鼠是 2 型糖尿病的模型。在存在生理底物的情况下，评估了能量代谢、一氧化氮（NO）途径和心脏功能的变化。年龄匹配的对照组 Wistar（n = 19）和 GK（n = 18）分离大鼠心脏用 0.4 mM 棕榈酸、3%白蛋白、11 mM 葡萄糖、3 U/l 胰岛素、0.2 mM 丙酮酸和 0.8 mM 乳酸灌注 24 分钟，然后在 32 分钟低流量（0.5 ml·min(-1)·g 湿重(-1))缺血期间切换至 1.2 mM 棕榈酸（每组 11 只大鼠）。接下来，用 0.4 mM 棕榈酸缓冲液恢复 32 分钟的流量。每组的一部分心脏（对照组 n = 8，GK 组 n = 7）在初始灌注 24 分钟后进行冷冻夹闭，以确定基线值。使用 (31)P 磁共振波谱法同时测量收缩功能，跟踪 ATP、磷酸肌酸 (PCr) 和细胞内 pH（pH(i)）。通过测定心脏中一氧化氮合酶（NOS）同工型表达和总硝酸盐浓度（NOx）来确定 NO 途径。我们发现，与对照组大鼠心脏相比，GK 大鼠心脏在基线条件下的冠状动脉流量降低了 26%（P < 0.05），在再灌注期间降低了 61%（P < 0.05）。与对照组大鼠心脏相比，GK 大鼠心脏在再灌注期间的心率血压乘积降低（P < 0.05）。在两组中，缺血再灌注期间的 ATP、PCr 和 pH(i) 相似。在基线条件下，GK 大鼠心脏内皮型一氧化氮合酶表达增加（P < 0.05）。在基线条件下（P < 0.05）和再灌注后（P < 0.05），GK 大鼠心脏的 NOx 增加。我们报告说，2 型糖尿病 GK 大鼠心脏对缺血性损伤的易感性增加，这与能量代谢受损无关。冠状动脉流量减少、eNOS 表达上调和总 NOx 水平增加证实了该模型中 NO 途径的改变，可能与氧化应激增加有关。NO 途径的改变可能在 2 型糖尿病 GK 大鼠心脏的缺血再灌注损伤中起主要作用。
