Age dependency of the effects of dietary sodium restriction on blood pressure in spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR) were placed on sodium restricted diets (9 and 17 mumol/g) or on a regular sodium diet (101 mumol/g) at 2, 7 and 10 weeks of age, and continued until 16 weeks of age. Sodium restriction initiated at 2 weeks prevented (9 mumol/g) or attenuated (17 mumol/g) the development of hypertension, and severely retarded growth. When sodium restriction was started at 7 weeks, these effects were not so pronounced. Starting at 10 weeks, sodium restriction no longer affected blood pressure, although growth rate was still reduced. These results indicate that there is a period early in life in SHR during which hypertension development critically depends on a minimum amount of sodium intake.