Blood pressure of rats as affected by diet and concentration of NaCl in drinking water.

In the first experiment, weanling rats were fed a grain ration or one of three semipurified diets high in fat, sucrose, or cornstarch. Rats in each dietary group were divided into two subgroups, one of which drank distilled deionized water whereas the other group drank 2% NaCl solution. Blood pressure and sodium intake were individually measured for each rat at weekly intervals for a 10-week period. Rats receiving the salt solution had higher mean blood pressures (127-178 mmHg) than rats offered distilled water (108-127 mmHg). When drinking solutions were the same, more severe rises in blood pressure occurred in rats fed the semipurified diets than in those rats fed grain. In a second experiment, rats were fed one of the four diets used in the first experiment; however, they received a 1% NaCl drinking solution for 9 weeks followed by a 1.5% NaCl solution for an additional 9 weeks. At Week 18, pressures among these groups of rats ranged from 136-140 mmHg, regardless of diet.