RESUMO
Despite the extensive research on the pharmacology of L-arginine, there are only few data on its antithrombotic properties. We studied the effect of oral L-arginine administration in a model of arterial thrombosis in rabbits divided into three groups: group 1, group without intervention; group 2, control group, treated with normal diet and submitted to the thrombosis-triggering protocol; group 3, treated for 2 weeks with L-arginine (2.25%) prior the protocol. L-Arginine did not alter platelet aggregation nor coagulation parameters but reduced vascular activities of both ADPase (49.1 +/- 8.5 versus 28.9 +/- 8.3 versus 18.8 +/- 10.3 nmoles inorganic phosphate/min per mg protein; mean +/- SD; group 1 versus group 2 versus group 3, respectively; ANOVA F = 19.21; P < 0.0001) and ATPase (97.8 +/- 15.8 versus 52.1 +/- 11.6 versus 31.9 +/- 16.3 nmoles inorganic phosphate/min per mg protein; mean +/- SD; group 1 versus group 2 versus group 3, respectively; ANOVA, F = 34.65; P < 0.0001). L-Arginine did not reduce the thrombi area (17.1 mm, 9.02 and 48.07, versus 27.04 mm, 25.4 and 70.39, median, percentile 25 and 75 respectively, P = 0.079; group 2 versus group 3, respectively). In conclusion, oral L-arginine administration did not inhibit thrombosis, and, conversely, it significantly reduced the arterial wall ADPase and ATPase activities. This effect may limit its antithrombotic properties.