O-2 TRANSFER KINETICS IN A WHOLE-BLOOD UNICELLULAR THIN-LAYER

A planar monocellular layer of whole blood (WB) sandwiched between two Gore-Tex membranes is used to study O2 uptake and release kinetics at 37°C. Gore-Tex, a highly gas-permeable open mesh of Teflon fibrils (78% porosity, 0.2-μm pore size, 75-μm thick), constrains WB to form a thin film without imposing an appreciable gas diffusion barrier. WB layer thickness, measured by isotope dilution, is 1.7 ± 0.2 μm. WB films are mounted between fiber optics in a gas flow tube for dual-wavelength (536/558 nm) oxyhemoglobin saturation measurements after a step change in PO2. For isocapnic (6% CO2) step changes in PO2 between 0 and 104 Torr, WB O2 uptake half time is 10.4 ± 0.9 ms; WB O2 release half time is 20.6 ± 2.4 ms. Half-time values are half of those previously reported. The thin-layer method reduces erythrocyte diffusion boundary layer error and thereby offers an attractive alternative to classical rapid fluid-mixing techniques.