Blood, plasma, and red cell volumes: age, exercise, and environment.

Abstract

Observa-tions have been made on blood components of seven men in the hot desert and on two of them at 3,800 m 1 week after leaving the desert. Similar observations made in the desert on Dill 32 years before are recorded. No notable change occurred in blood components at rest during the first days in the desert; even in a bout of exercise there generally were no changes. In two men who engaged in frequent strenuous exercise during a 5-week period there was a decline to al red cell volume and an increase in plasma volume with no change in blood volume. These two men, Phillips age 34 and Dill age 73, then made the transition to the Barcroft laboratory with a decrease in barometric pressure from 694 to 485 mm Hg and in maximum temperature from above 40 to about 15 C. Phillips showed an increase in hemoglobin concentration and a decrease in plasma volume. Dill had a decrease in hemoglobin concentration and an increase in plasma volume. In the light of this and other evidence it appears that the response of plasma volume in the first days at high altitude is to decline in youth and to increase in age. From age 41 to age 73, Dill''s plasma volume has decreased about one-sixth and red cell volume about 6%.