title: An in vitro capillary system for studies on microcirculatory O2 transport.
abstract: An in vitro artificial capillary system has been developed for use in examining the O2 transport properties of free hemoglobin and erythrocytes. The artificial capillary was constructed by casting a thin film of transparent silicone rubber around a strand of tungsten wire that was 24 micron in diameter. After the rubber had polymerized, the wire was removed. Typical dimensions of the silicone rubber film were 170 micron thick, 1 cm wide, 5 mm long in the direction of flow, and a 27-micron lumen diameter. The artificial capillary bed was mounted on a microscope and perfused by either hemoglobin solutions or cell suspensions. Fractional saturation was measured as a function of axial position by a dual-wave-length microspectrophotometer, and the flow rate was regulated precisely by a syringe pump. O2 release experiments were carried out by suffusing the gas space surrounding the artificial capillary film with 100% N2 and perfusing with an oxygenated sample. O2 uptake experiments were carried out by suffusing the gas space with O2-N2 mixtures and perfusing with deoxygenated samples. The axial velocities were varied from 3 to 15 mm/s. The residence time (the time a particular red cell or hemoglobin molecule has spent in the capillary) for 50% oxygenation of a 4 mM (heme) deoxyhemoglobin solution was approximately 0.05 s at 37 degrees C when the gas space surrounding the capillary contained air. The corresponding time for 50% oxygenation of an equivalent red cell suspension was approximately 0.25 s.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D001692:Biological Transport; D002196:Capillaries / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008955:Models, Cardiovascular; D010100:Oxygen / Q000097:blood*; D012996:Solutions
chemical_list: D006454:Hemoglobins; D012996:Solutions; D010100:Oxygen