l-NAME-treatment alters ectonucleotidase activities in kidney membranes of rats

AimsTo investigate the effect of Nω-Nitro-l-arginine methyl ester (l-NAME) treatment, known to induce a sustained elevation of blood pressure, on ectonucleotidase activities in kidney membranes of rats.Main methodsl-NAME (30 mg/kg/day) was administered to Wistar rats for 14 days in the drinking water. Enzyme activities were determined colorimetrically and their gene expression patterns were analyzed by semi-quantitative RT-PCR. The metabolism of ATP and the accumulation of adenosine were evaluated by HPLC in kidney membranes from control and hypertensive rats. PKC phosphorylation state was investigated by Western blot.Key findingsWe observed an increase in systolic blood pressure from 115 ± 12 mmHg (control group) to 152 ± 18 mmHg (l-NAME-treated group). Furthermore, the hydrolysis of ATP, ADP, AMP, and p-Nph-5′TMP was also increased (17%, 35%, 27%, 20%, respectively) as was the gene expression of NTPDase2, NTPDase3 and NPP3 in kidneys of hypertensive animals. Phospho-PKC was increased in hypertensive rats.SignificanceThe general increase in ATP hydrolysis and in ecto-5′-nucleotidase activity suggests a rise in renal adenosine levels and in renal autoregulatory responses in order to protect the kidney against the threat presented by hypertension.