Effects of l-arginine administration before cardioplegic arrest on ischemia-reperfusion injury

Background. Administration of l-arginine during reperfusion or its addition to cardioplegic solution has been shown to protect myocardium against ischemia-reperfusion injury. This study aimed at evaluating the role of l-arginine in ischemia-reperfusion injury when administered intraperitoneally 24 hours before cardioplegic arrest.Methods. Two groups of Sprague-Dawley rats (control, n = 10; and l-arginine, n = 10) were studied in an isolated buffer-perfused heart model. Both groups were injected intraperitoneally 24 hours before ischemia. Before experimentation blood samples were collected for cardiac troponin I and cGMP analysis. In the coronary effluents, cardiac troponin I, adenosine, cyclic guanosine monophosphate, and nitric oxide metabolites were assayed.Results. Before heart excision, serum cardiac troponin I concentrations were higher in the l-arginine than in the control group (0.037 ± 0.01 versus 0.02 ± 0.05 μg · L⁻¹; p < 0.05). During reperfusion, cardiac troponin I release was lower in the l-arginine than in the control group (0.04 ± 0.01 versus 0.19 ± 0.03 ng · min⁻¹; p < 0.05). The coronary flow as well as the left ventricular developed pressure were higher in the l-arginine than in the control group before ischemia and remained so throughout the experimentation.Conclusions. These results indicate that l-arginine administered intraperitoneally 24 hours before cardioplegic arrest reduced myocardial cell injury and seems to protect myocardium against ischemia-reperfusion injury.