Effect of age on transvascular fluid movement

Swellings of the mouse tail and ear were produced by subjecting them to subatmospheric pressures of minus 40 to minus 80 mmHg for 15-60 min. Increase in volume was measured volumetrically in the tail and gravimetrically in the ear. Blood volume increases in the tail, as measured with 51Cr erythrocytes, contributed a minor part of the fluid increase. Comparison of mice from 3 to 36 wk in age showed a large decrease of fluid movement with age, with major changes during the growth period. Study of permeability of the ear under decreased pressure,to intravenously administred Evans blue, showed no influence of age on permeability to the protein-bound dye. Measurement of transmission of the applied negative pressure through the skin, and of compliance of the tissues of the ear and tail in mice of different age groups, indicated that these factors were not responsible for the observed changes with age.