Oxygen diffusion coefficient of cell membranes.

Abstract

The microviscosity was measured in erythrocyte membranes of different animal species and in lung cells and myocytes of bull frogs by means of the nanosecond fluorescence depolarization technique with a rod-like fluorescent probe, 1,6-diphenyl-1,3,5-hexatriene (DPH). The diffusion coefficient of oxygen molecules (DO2) was estimated from the microviscosity and an equation for the relation between viscosity and diffusion coefficient. The DO2 value of erythrocyte ghosts was remarkably different among species; 0.84 in sheep, 1.29 in human, 1.49 in rat and 1.92 X 10(-7) cm2/sec in rabbit, while the wobbling diameter Wd was 10.7, 11.5, 12.1 and 10.7A in respective species. The DO2 value in frogs was different among organs; 1.07 in erythrocyte ghosts, 2.18 in lung cells, 2.64 X 10(-7) cm2/sec in myocytes. The Wd value was 12.2, 12.6 and 13.4A in respective organs at 30 C. A comparison between sizes of moving area of phospholipid molecules in membrane and in ideal fluid state suggested that the actual DO2 values in cell membranes may probably be ten times larger than the present values.