The influence of high and low sodium intake on blood volume in the dog.

Plasma volume and blood volume were measured using T-1824 in two groups of dogs which were kept on a diet differing only in its content of sodium chloride for periods exceeding six weeks. The group on low sodium intake received 0.55 mmol Na.g-1.day-1 and the group on high sodium intake received 12.4 mmol Na.g-1.day-1. Both plasma and blood volumes were distinctly greater in the group on high sodium intake than those in the group on low sodium intake, and there was no differences in the haematocrit between the two groups of dogs. It is concluded that a greater plasma volume and red cell volume resulted from high sodium intake than from low sodium intake.