The effects of renal dopaminergic system on the development of hypertension with high salt diet and L-NNA administration

Objective: We aimed to investigate the intrarenal dopamine synthesis efficiency, blood pressure changes and the effects of this system on hypertension developed by NOS inhibition and high salt diet. Method: Wistar Albino male rats were administered water containing 50mg/L or 100mg/L concentrations of L-NNA, standard rat feed containing 0.8%salt, or 4%high salt alone or with L-NNA for 7days. Blood pressure measurements were made with the tail-cuff method. 24-hour water intake and urine volume were also measured. Results: Administration of L-NNA or high-salt diet alone for 7days did not cause a change in blood pressure, while their combined administration resulted in a significant increase in blood pressure. Blood pressures were found to be higher in the L-NNA100+HS group compared to the other groups. While the amount of water intake in 24hours did not change, the amount of 24-hour urine was reduced. 24-hour urinary sodium excretion, sodium clearance and GFR was decreased, and 24-hour urine dopamine concentrations were increased. Conclusion: Co-administration of nitric-oxide inhibitor and high-salt diet failed to prevent renal dopaminergic system blood pressure increase. Despite the increase in dopamine synthesis, intrarenal dopamine activity could not be realized by receptor interaction and it is thought that the increase in blood pressure is caused by the development of renal oxidative stress.