[Determination of the rate of oxygen release from flowing erythrocytes in a microvessel--development of an apparatus and the application to microvessels of rat mesentery].

An apparatus for determining the rate of oxygen release from flowing erythrocytes in microvessel was developed by attaching the following units to an inverted microscope. 1) A scanning spectrophotometer, equipped with a grating and a photon counter, was connected with a narrow light-guide, as to obtain the absorption spectrum (wave length range: 450 approximately 650 nm) of a focused spot (of 5 microns diameter), and then to calculate hemoglobin concentration and the oxygen saturation. 2) To measure the velocity of erythrocyte flow by dual-spots cross-correlation method, two photomultipliers (joined to an analog-digital converter and a personal-computer) were connected to the microscope with two light-guides. 3) An image-processor was used to estimate the diameter of vessel from the digitized video-images. The performance of the apparatus was examined with hemoglobin solution and erythrocyte suspension (by flowing through rectangular capillary tubes). The apparatus was applied for microvessels of rat mesentery to determine the rate of oxygen release from flowing erythrocytes. The rate was maximum in capillaries, and the rate in microvessels of arterial side was greater than that in microvessels of venous side ones.