ABSTRACT
BACKGROUND: There are studies showing stimulative effect of arginine on insulin secretion. This mechanism is not fully explained. The effects of the impact of arginine on carbohydrate balance under the conditions of ischemia and reperfusion remain to be determined. The aim of this study is the evaluation of the influence of short-term L-arginine supplementation on the concentration of glucose and insulin in blood and insulin binding in rat skeletal muscle under the conditions of ischemia and reperfusion. METHODS: The study was conducted on male Wistar rats with average body mass 250 ± 30 g. Animals were divided into four groups: Group I - control, Group II - placebo, Group III - L-arginine 500 mg/kg/24 h for 5 days, Group IV - L-arginine and L-NAME (75 µmol/rat/24 h) for 5 days. Each group was divided into subgroups depending on duration of ischemia and reperfusion. Acute ischemia of hind limb was induced in each group by putting pneumatic tourniquet on the thigh. Blood samples and skeletal muscles were collected from the rats. Plasma concentrations of glucose and insulin were measured. Insulin binding to insulin receptors was determined in skeletal muscle. RESULTS: A clear reduction of insulin binding to receptor was found in the group of animals without ischemia and the group supplemented with L-arginine and subjected to 4-h ischemia and 30- and 120-min reperfusion. A significant increase in insulin level was found in groups of animals with L-arginine and/or L-NAME subjected to 4-h ischemia at all times of reperfusion. Supplementation with L-arginine and/or L-NAME decreased levels of glucose in blood serum of animals undergoing ischemia-reperfusion syndrome compared to the control and placebo groups. CONCLUSION: Under conditions of ischemia-reperfusion, short-term administration of L-arginine causes a decrease in insulin binding capacity of insulin receptors in skeletal muscle, an increase in insulin level and a decrease in the concentration of glucose in blood serum.
Subject(s)
Arginine/pharmacology , Blood Glucose/drug effects , Insulin/metabolism , Reperfusion Injury/drug therapy , Animals , Hindlimb/blood supply , Insulin/blood , Male , Muscle, Skeletal/drug effects , Muscle, Skeletal/metabolism , NG-Nitroarginine Methyl Ester/pharmacology , Rats , Rats, Wistar , Receptor, Insulin/metabolism , Reperfusion Injury/physiopathology , Time FactorsABSTRACT
Due to the complex mechanisms of L-arginine activity, it is difficult to determine the clinical significance of supplementation with this amino acid. The objective of this study was to determine the influence of short-term supplementation with L-arginine in stress conditions, induced by ischemia-reperfusion syndrome, by assessing the damage to muscular and hepatic cells on the basis of creatine kinase (CK), alanine aminotransferase (ALAT) and aspartic aminotransferase (AspAT) activity in blood and the level of oxygen free radicals in analyzed tissues of rats. We observed that induced ischemia of hind limb caused an increase in CK, ALAT and AspAT activity and an increase in the level of free radicals in liver, but not in skeletal muscle. Supplementation with L-arginine led to a reduction in serum activity of CK and AspAT and reduction of the level of free radicals in analysed tissues. Simultaneous supplementation with L -arginine AND L-NAME resulted in a reversal of changes induced by L-arginine supplementation in the case of AspAT and free radicals in skeletal muscle. The results indicate that under conditions of ischemia-reperfusion, short-term administration of L-arginine has a protective effect on skeletal muscle manifesting itself by reduction of CK in the serum and reduction of free radicals level in THIS tissue.
