Age-related changes in the protective effect of chronic administration of l-arginine on post-ischemic recovery of endothelial function

Objective: The aim of this study was to assess the effect of chronic administration of L-arginine (LA) on vascular functions as well as its age-related changes. Methods: Male Sprague– Dawley rats aged 1, 4, 8 and 16 months were divided into control and LA groups, which were administered LA (4 mg/ml) for 6 weeks. Isolated heart perfusion was performed, followed by cardioplegic arrest for 4 h at 48C and reperfusion. Vascular functions were assessed through observations of pre-/post-ischemic coronary flow response to 5-hydroxytryptamine (5-HT) and glyceryl trinitrate (GTN). Ultrastructure was studied after the same ischemia-reperfusion. Results: A significant improvement of percentage recovery (post-/pre-ischemic value) of response to 5-HT were seen in 4 and 8 months LA group when compared to the control (84.2 ^ 14.0 vs. 33.9 ^ 12.5 ðP , 0:05Þ and 97.0 ^ 23.2 vs. 21.5 ^ 9.7 ðP , 0:05Þ, respectively). Furthermore, 8 months LA group had better percentage recovery of response to GTN (124.5 ^ 41.6 vs. 47.7 ^ 6.3, P , 0:05). Ultrastructural study showed no significant differences between the groups in any age. Conclusions: Chronic oral administration of LA enhanced the post-ischemic recovery of vascular function in the young adult and adult hearts, but not in the infant and elderly. q 2003 Elsevier Science B.V. All rights reserved.