The aim was to investigate the effects of L-arginine and N-acetyl-L-cysteine on the structural and functional characteristics of cardiovascular system parameters in rats with experimental type 1 diabetes mellitus (DM1).

Methods and techniques. DM1 was induced in old male Wistar rats by a single 45 mg/kg streptozotocin. After 6 weeks, animals with DM1 were divided into 3 subgroups: without amino acid administration, rats with L-arginine and rats with N-acetyl-L-cysteine. To achieve the aim, blood pressure measurements and echocardiography were performed.

Results. In rats with DM1, a significant increase in systolic (by 24 %) and diastolic (by 17 %) blood pressure was observed at the 6th week of the experiment. Left ventricular dilatation was also found, accompanied by an increase in end-diastolic (by 20 %) and end-systolic (by 61 %) volumes, as well as a decrease in ejection fraction (by 6 %). At week 8, in rats without correction, blood pressure continued to increase (systolic by 7 %, diastolic by 9 %), and systolic dysfunction also progressed. Administration of L-arginine for 2 weeks normalized blood pressure (decrease by 12–16 %) and reduced left ventricular dilatation. L-arginine also improved systolic function (increase in ejection fraction by 6 %). N-acetyl-L-cysteine also reduced pressure but had no significant effect on echocardiographic parameters.

Conclusions. Against the background of the development of experimental type 1 diabetes mellitus in rats, cardiomyopathy with dilatation of the left ventricle and a decrease in its systolic function is formed by the 6th week. These changes occur in parallel with a significant increase in blood pressure and a decrease in heart rate. In rats with experimental diabetes mellitus, after 8 weeks, signs of left ventricular dilatation remained without statistically significant changes compared to the indicators of the 6th week, however, progression of systolic dysfunction was observed against the background of a further increase in blood pressure. Administration of L-arginine to rats with diabetes mellitus for 2 weeks statistically significantly reduced blood pressure and decreased manifestations of left ventricular dilatation comparable to rats with diabetes mellitus of 8 weeks duration without correction. Administration of N-acetyl-L-cysteine reduced blood pressure in the corresponding subgroup, however, no statistically significant effect on echocardiographic parameters was found compared to the 8-week group without correction.