Ischemic preconditioning attenuates acidosis and postischemic dysfunction in isolated rat heart

Abstract

The hypothesis that brief ischemia (preconditioning) protects the isolated heart from prolonged global ischemia was tested. Isovolumic rat hearts were preconditioned with either 5 min of ischemia followed by 5 min of perfusion (P1) or two 5-min episodes of ischemia separated by 5 min of perfusion (P2). Control hearts received no preconditioning. All hearts received 40 min of sustained ischemia and 30 min of reperfusion. Preconditioning (P1 or P2) significantly (P less than 0.0005) improved recovery of the rate-pressure product; percentage recoveries were 17.8 +/- 3.2 (n = 14), 59.9 +/- 5.5 (n = 6), and 46.4 +/- 4.7 (n = 8) for control, P1, and P2, respectively. Improved functional recovery of preconditioned hearts was associated with reduced end-diastolic pressure and improved myocardial perfusion. During the 40-min ischemic period, myocardial pH decreased from approximately 7.4 to 6.3 +/- 0.1 (n = 7) in the control hearts and to 6.7 +/- 0.1 (n = 7) in the preconditioned hearts (P less than 0.01). Also during the 40-min ischemic period, myocardial lactate (expressed as nmol/mg protein) increased to 146 +/- 11 (n = 7) and 101 +/- 12 (n = 8) in control and preconditioned hearts, respectively (P less than 0.02). The results demonstrate that a brief episode of ischemia can protect the isolated rat heart from a prolonged period of ischemia. This protection is associated with decreased tissue acidosis and anaerobic glycolysis during the sustained ischemic period.

In vivo Spectroscopy and Imaging of Nitroxide Probes

“…As seen in Figure 13 ischemic preconditioning improved pH homeostasis during the global no-flow ischemia. Similar kinetics of myocardial acidification observed by the cell-impermeable RSG and cell-permeable IR2 probes support fast pH equilibration between intracellular and extracellular spaces in agreement with data obtained previously using glass microelectrodes and 31 P-NMR (Asimakis et al, 1992;Lundmark et al, 1999). Figure 13.…”

Ischemic preconditioning of rat livers against cold storage-reperfusion injury: Role of nonparenchymal cells and the phenomenon of heterologous preconditioning

“…22 Ischemic preconditioning also protects against arrhythmias and cardiac contractile dysfunction induced by ischemia and reperfusion. 23,24 Recently, ischemic preconditioning was shown to protect hearts and lungs stored for transplantation against injury induced by cold ischemic storage and reperfusion. 25,26 In livers, ischemic preconditioning decreases hepatic enzyme release and mortality after warm ischemia and reperfusion.…”

Medical and Cellular Implications of Stunning, Hibernation, and Preconditioning

“…178,179 However, the efficacy of ischemic preconditioning in reducing arrhythmias and stunning has not been as consistent as its ability to reduce necrosis. Furthermore, it is unknown whether the protection afforded by preconditioning against arrhythmia and stunning is mediated by the same mechanism that mediates its protection against lethal cell injury.…”