Solubility of various inert gases in rat skeletal muscle

For the determination of solubility coefficients, isolated rat abdominal muscles were equilibrated at 37 degrees C with various inert gases saturated with water vapor. After rapid transfer into a closed chamber containing room air the amount of gas extracted from the sample by diffusion was measured by gas chromatography. Corrections for unextracted gas and for gas lost during the transfer of the sample were applied. The following mean values for the solubility coefficients, in mumol-1(-1)-torr(-1), were found: chloro-difluoro-methane (Freon 22), 56.0; acetylene, 55.5; nitrous oxide, 27.7; methane, 2.42; hydrogen, 1.13; helium, 0.608; sulfur hexafluoride, 0.559. The relationships between solubility in tissue, in water and in olive oil are discussed.

Diffusivity of various inert gases in rat skeletal muscle

Krogh’s diffusion constant (K) was determined for various inert gases in isolated rat abdominal muscle at 37 degrees C by measuring the amount of gas diffusing per unit time and partial pressure difference through a portion of the muscle of known surface area and thickness. The following mean values for K, in 10(-9) mmol-min-1-cm-1-torr-1, were obtained: C2H2, 42.2; N2O, 20.0; CHClF2, 18.8; H2, 1.67; He, 1.42; CH4, 1.27; SF6, 0.081. From Krogh’s diffusion constant, the diffusion coefficient (D) was calculated using the solubility coefficient determined previously in the same preparation. The D values thus obtained were found to be about half the D values in water at 37 degrees C. Model calculations show that for gases with high lipid/water partition coefficient, D in tissues containing lipid is underestimated by this method. Graham’s law (inverse proportionality between D and square root of molecular mass) was found to represent a useful approximation for these gases. A better correlation, however, was obtained between D and the molecular diameter.

Solubility of inert gases in dog blood and skeletal muscle

Solubility of H2, Ar, CH4 and SF6 was determined at 310 K (37 degrees C) in water, in saline (0.154 mol NaCl/l H2O), in plasma and whole blood of dogs, and in homogenates of the dog gastrocnemius muscle. The liquids were equilibrated with pure gases, and the dissolved gases were extracted and measured by gas chromatography as described previously (Meyer, M.: Pflügers Arch. 375, 161–165, 1978). In saline, the solubilities were 4% (SF6) to 15% (Ar) lower than in water. For dog blood the following mean values for the solubility coefficient (in mumol . 1(-1) . kPa-1) were found: for H2, 6.44; for Ar, 9.94; for CH4, 11.44; for SF6, 2.62. The red cell/plasma and the muscle/blood solubility ratios were near unity for H2, Ar and CH4 (ranging from 0.9 to 1.3); for SF6, however, they were much higher (about 2.1), apparently due to the high solubility of SF6 in hydrophobic substances (lipids).