The rate of oxygen release from single sinusoid of rat liver, determined by microspectroscopy

The rate of oxygen release from single hepatic sinusoid of rat was determined. A scanning spectrophotometer, equipped with a grating and two photoncounters, was connected to a microscope with light-guides, and absorption spectra (450-650 nm) were obtained simultaneously at two microspots (10 microns diameter) on single sinusoid. The concentration ([Hb]) and oxygen saturation (SO2) of hemoglobin were calculated from the spectra. Reference transmittance was obtained at neighbouring hepatocytes. The erythrocyte velocity was measured by dual-spots cross-correlation method using two photomultipliers connected to the microscope with two light-guides. The gradient in SO2 was observed along each sinusoid, due to oxygen release from flowing erythrocytes to hepatocytes. The rate of oxygen release per unit surface area was 0.24 +/- 0.14(n = 14)nmoles O2/cm2/sec, which was calculated from [Hb], difference in SO2 between the spots at up- and down-stream, erythrocyte velocity, two spot's distance and sinusoidal diameter. The rates of O2 release depended on sinusoidal diameter and sinusoidal blood flow.