Elevated 22Na uptake in aortae of Dahl salt-sensitive rats with high salt diet

We examined the effects of high salt intake on blood pressure and vascular 22Na uptake in Dahl salt-sensitive (DS) rats. At 6 weeks of age, one group of 6 DS rats was placed on a low (0.4%) salt diet and the second group of 6 DS rats was placed on a high (8.0%) salt diet for a period of 4 weeks. Blood pressure recordings were made weekly. At 10 weeks of age, the animals were sacrificed and aortic 22Na uptake was measured. Total and amiloride sensitive (Na(+)-H+ antiport) components of 22Na uptake were measured from which was calculated the amiloride insensitive component. Na+, K(+)-pumps were inhibited for these vascular 22Na uptake experiments with ouabain to prevent Na+ efflux. DS rats on the high salt diet demonstrated significantly (P less than 0.01) higher blood pressure when compared to DS rats on a low salt diet. Similarly, DS rats on a high salt diet demonstrated significantly (P less than 0.05) higher total, amiloride sensitive and amiloride insensitive vascular 22Na uptake as compared to DS rats on low salt diet. The parallel increase in vascular 22Na uptake and blood pressure suggests a possible, key role of Na+ influx in the mechanism of salt induced hypertension of DS rats.