Left ventricular mass and fluid compartmentalization in Wistar-Kyoto and spontaneously hypertensive rats fed high- or low-sodium diet.

Our purpose was to test the hypothesis that a high sodium intake promotes fluid volume expansion, and hence weight gain, in the left ventricle. Between 6 and 30 weeks of age, Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) were fed low-, control- or high-sodium chow. After treatment, known quantities of 22NaCl and Na2(35)SO4 were injected intravenously into each animal and permitted to equilibrate with body fluids in order to measure sodium and sulphate spaces in various tissues. Fluid spaces in left ventricle, as well as in right ventricle, skeletal muscle, kidney and whole-body, of high-sodium groups were similar to those of control- or low-sodium groups. We conclude that high intake of dietary sodium is a factor that promotes myocardial hypertrophy, and the mechanism appears to be independent of arterial blood pressure and intravascular volume.