Partition of xenon and iodoantipyrine among erythrocytes, plasma, and myocardium.
A new method was developed for determining directly the distribution of 133Xe between red cells and plasma in vitro without an air-fluid interface; the partitioning of 133Xe and 133-i-iodantipyrine between blood and myocardium was investigated in the dog in situ. The red cell-plasma partition coefficient for 133Xe (lambdacpX, unit: ml/ml) at 37 degrees C was 2.27 +/- 0.07 (mean +/- SD) for human blood and 3.31 +/- 0.06 for dog blood. The red cell-plasma partition coefficient for 131I-iodantipyrine (lambdacpI, ml/ml) was 0.75 +/- 0.04 for human blood and 0.97 +/- 0.03 for dog blood. lambdacpX and lambdacpI did not change significantly after the intravenous administration of sodium pentobarbital (30 mg/kg) into the dog. lambdacpX of dog blood varied inversely with temperature, whereas lambdacpI showed very little change with temperature. The blood-left ventricle partition coefficient for 133Xe (lambda'btX, corrected for trapped blood) varied directly with directly with red cell volume fraction (H): lambda'btX = 1.32 + 2.00 H. Blood-left ventricle partition coefficient for 131I-iodoanitpyrine did not vary significantly with H. The results support the concept of a three-compartment partition of the indicator among erythrocytes, plasma, and myocardium. The mean values (+/- SD) of the hematocrit-independent plasma-tissue partition coefficient in the left ventricle for 133Xe and 131I-iodoantipyrine were 1.08 +/- 0.16 and 1.54 +/- 0.20 g/ml, respectively.
D000771:Anesthesia, Intravenous; D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*; D004285:Dogs; D004912:Erythrocytes / Q000378:metabolism*; D006400:Hematocrit; D006801:Humans; D007457:Iodine Radioisotopes; D050356:Lipid Metabolism; D009206:Myocardium / Q000378:metabolism*; D010424:Pentobarbital / Q000494:pharmacology; D010949:Plasma / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000378:metabolism; D014980:Xenon Radioisotopes / Q000378:metabolism*
D007457:Iodine Radioisotopes; D014980:Xenon Radioisotopes; D014867:Water; D010424:Pentobarbital; D000983:Antipyrine