Dietary L-arginine supplementation normalizes regional blood flow in Dahl-Iwai salt-sensitive rats

We performed the present study to determine 1) whether different organs undergo similar increase in vascular resistance in Dahl-Iwai salt-sensitive (S) rats, and 2) the effects of chronic oral L-arginine supplementation on the regional hemodynamics in S rats. Male 6 week old S rats and Dahl-Iwai salt-resistant (R) rats were maintained on an 8% NaCl chow for 4 weeks. One group (S or R rats) was maintained on tap water and the other group (S/Arg) of S rats received tap water containing L-arginine at a concentration of 1.5%. Organ blood flow and cardiac output were measured with microspheres in the conscious condition. Concerning regional hemodynamics, the flow rate of the kidney was lower in S rats than in R rats, but there were no differences between S and R rats in the flow rates of the brain, heart, lung, liver, spleen, intestine, skeletal muscle and skin. The flow rate of the kidney in S/Arg rats was maintained at a higher level as compared to that of S rats. Urinary excretion of protein and albumin in S/Arg rats was significantly suppressed when compared to S rats. Thus, the supplementation of L-arginine normalized the abnormality of renal hemodynamics accompanying salt-induced hypertension. It is suggested that the disturbance in the production of nitric oxide may induce salt-sensitive hypertension and the abnormality of renal hemodynamics in the S rats.