The effect of L-arginine and L-NAME on myocardial capillary density in normal rats

Background: This study evaluated the effect of L-arginine (Nitric Oxide (NO) precursor) and L-NG-Nitroarginine Methyl Ester (L-NAME) (NO synthase inhibitor) on myocardial capillary density in normal rats.

Materials and methods: EIGHTEEN MALE RATS WERE DIVIDED INTO THREE GROUPS: Group 1: Received L-NAME (10 mg/kg/day; ip), Group 2: Received L-arginine (50 mg/kg/day; ip), and Group 3 (control) received normal saline. After 3 weeks, blood samples were taken and myocardial capillary density was evaluated using immunohistochemistry method.

Results: Serum NO concentration in control group was 6.45 ± 0.44 μmol/lit. Treatment of animals with L-arginine increased serum NO concentration (7.90 ± 0.75 vs. 6.45 ± 0.44 μmol/lit, respectively) and L-NAME decreased (4.86 ± 0.40 vs. 6.45 ± 0.44 μmol/lit, respectively) compare to control group. L-arginine significantly increased serum vascular endothelial growth factor (VEGF) concentration (353.01 ± 7.03 vs. 100.5 ± 6.61 pg/ml; P < 0.05), however, did not change myocardial capillary density.

Conclusion: Although L-arginine alters some serum angiogenic factors, either L-arginine or L-NAME could not improve myocardial capillary density in normal rats.