RESUMO
Under physiological conditions insulin controls the metabolism of carbohydrates, lipids and proteins. Diabetes mellitus is a metabolic disease characterized by a disturbance in the intermediary metabolism of glucose and glucose-induced insulin release. Arginase (L-arginine amidinohydrolase, EC 3.5.3.1) modulates nitric oxide synthase activity by regulating intracellular L-arginine availability. In diabetes mellitus, a decrease in nitric oxide bioavailability is a central mechanism for endothelial dysfunction. The aim of our study was to assess arginase activity in the blood of children with diabetes mellitus. Blood arginase activity, serum glucose (14.155 +/- 4.197 mmol/L; p < .001) and blood HbA1c (11.222 +/- 3.186 %; p < .001), were significantly higher in diabetic children than in healthy controls, whereas the magnesium (Mg2+) level, a cofactor of many enzymes, was significantly lower (0.681 +/- 0.104 micromol; p < .001). In diabetic children, arginase activity, hyperglycemia (r = 0.143), and the HbA1, level (r = 0.381) showed a positive correlation between but a negative correlation between Mg2+ and arginase activity (r= -0.206). The higher arginase activity and the lower Mg2+' levels in diabetic children could be a consequence of reduced insulin action and increased protein catabolic processes in these pathophysiological conditions. The inverse directions of arginase activity and serum Mg2+ levels are in agreement with this concept.