Bassenge E, Sommer O, Schwemmer M, Bünger R
Institute for Applied Physiology, University of Freiburg, D-79104 Freiburg/Breisgau, Germany.
Am J Physiol Heart Circ Physiol. 2000 Nov;279(5):H2431-8. doi: 10.1152/ajpheart.2000.279.5.H2431.
Myocardial ischemia-reperfusion is associated with bursts of reactive oxygen species (ROS) such as superoxide radicals (O(2)(-).). Membrane-associated NADH oxidase (NADHox) activity is a hypothetical source of O(2)(-)., implying the NADH concentration-to-NAD(+) concentration ratio ([NADH]/[NAD(+)]) as a determinant of ROS. To test this hypothesis, cardiac NADHox and ROS formation were measured as influenced by pyruvate or L-lactate. Pre- and postischemic Langendorff guinea pig hearts were perfused at different pyruvate/L-lactate concentrations to alter cytosolic [NADH]/[NAD(+)]. NADHox and ROS were measured with the use of lucigenin chemiluminescence and electron spin resonance, respectively. In myocardial homogenates, pyruvate (0.05, 0.5 mM) and the NADHox blocker hydralazine markedly inhibited NADHox (16 +/- 2%, 58 +/- 9%). In postischemic hearts, pyruvate (0.1-5.0 mM) dose dependently inhibited ROS up to 80%. However, L-lactate (1.0-15.0 mM) stimulated both basal and postischemic ROS severalfold. Furthermore, L-lactate-induced basal ROS was dose dependently inhibited by pyruvate (0.1-5.0 mM) and not the xanthine oxidase inhibitor oxypurinol. Pyruvate did not inhibit ROS from xanthine oxidase. The data suggest a substantial influence of cytosolic NADH on cardiac O(2)(-). formation that can be inhibited by submillimolar pyruvate. Thus cytotoxicities due to cardiac ischemia-reperfusion ROS may be alleviated by redox reactants such as pyruvate.
心肌缺血再灌注与活性氧（ROS）爆发有关，如超氧阴离子自由基（O₂⁻）。膜相关的NADH氧化酶（NADHox）活性被认为是O₂⁻的一个潜在来源，这意味着NADH浓度与NAD⁺浓度之比（[NADH]/[NAD⁺]）是ROS的一个决定因素。为了验证这一假设，我们测量了丙酮酸或L-乳酸对心脏NADHox和ROS形成的影响。对缺血前后的豚鼠心脏进行Langendorff灌注，灌注液中含有不同浓度的丙酮酸/L-乳酸，以改变细胞溶质中的[NADH]/[NAD⁺]。分别使用光泽精化学发光法和电子自旋共振法测量NADHox和ROS。在心肌匀浆中，丙酮酸（0.05、0.5 mM）和NADHox阻滞剂肼屈嗪显著抑制NADHox（分别为16±2%、58±9%）。在缺血后心脏中，丙酮酸（0.1 - 5.0 mM）剂量依赖性地抑制ROS，抑制率高达80%。然而，L-乳酸（1.0 - 15.0 mM）使基础和缺血后ROS增加了几倍。此外，L-乳酸诱导的基础ROS被丙酮酸（0.1 - 5.0 mM）剂量依赖性抑制，而不是被黄嘌呤氧化酶抑制剂奥昔嘌醇抑制。丙酮酸不能抑制黄嘌呤氧化酶产生的ROS。这些数据表明细胞溶质中的NADH对心脏O₂⁻形成有重大影响，亚毫摩尔浓度的丙酮酸可以抑制这种影响。因此，心脏缺血再灌注ROS引起的细胞毒性可能通过丙酮酸等氧化还原反应物得到缓解。
