Oxygen and carbon dioxide permeability of subcutaneous pockets

Journal/Book: Reprinted from THE AMERICAN JOURNAL OF PHYSIOLOGY Vol. 202 No. 1 January 1962. 1962;

Abstract: Naval Medical Research Institute National Naval Medical Center Bethesda Maryland; and Department of Physiology Harvard School of Public Health Boston Massachusetts Received for publication 3 July 1961. 1Present address: Dept. of Physiology Stanford University Stanford Calif. Uptake rate of a gas from a rat's subcutaneous gas pocket was divided by the surface area and by the apparent pocket-to-tissue tension difference to yield an exchange coefficient K'. Values in (ml X 10-4)/(min cm2 atm) were O2 6.6; CO2 r 50; and N2 2. Blood flow in adjacent tissue appeared to have little influence an uptakes of O2 and CO2 since the K'CO2 : K'O2 ratio indicated that the uptakes were governed by diffusion alone and drastic alteration of blood flow (death of the animal) decreased K'O2 by only 10 %. In contrast blood flow apparently affected N2 uptake. Because O2 and CO2 uptakes were not blond flow limited K'O2 and K'CO2 are estimates of true permeability coefficients; the calculated permeability coefficient for N2 is 3·3 (ml X 10-4)/(min cm2 atm). Comparison shows the pocket surface to be 1/50-1/150 as effective for O2 transfer as the lung. Finally corrections are calculated for pocket-to-tissue pO2 and pCO2 differences in gas pockets used for tissue tonometry. ___MH

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