title: Factors affecting the exchange of tocopherol between red blood cells and plasma.
abstract: The purpose of this study was to clarify factors that affect the equilibrium distribution of alpha-tocopherol between red blood cells and plasma. Plasma labeled with 14C-alpha-tocopherol was incubated with red cells for 4 to 6 hr and the distribution of the tocopherol determined in the two compartments (red blood cell (RBC: plasma ratio). Use of heparin as anticoagulant gave a higher RBC: plasma ratio than acid citrate dextrose. The RBC:plasma ratio was affected by the hematocrit of the incubation mixture, higher ratios being obtained with lower hematocrits. The ratio was not related to the plasma concentration of alpha-toxopherol, indicating that the red cell was not saturated up to four times normal plasma levels. Of possible clinical significance was the finding that the RBC: plasma ratio was related to the total lipid concentration of plasma. Red cell content of alpha-tocopherol decreased as plasma lipids increased, until at three times normal plasma lipid concentration the red cells had one-third or less of their normal concentration of alpha-tocopherol. The implications of this observation on the relationship between plasma and tissue aplha-tocopherol are discussed.
mesh_terms: D000818:Animals; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006400:Hematocrit; D006493:Heparin / Q000494:pharmacology; D006949:Hyperlipidemias / Q000097:blood; D008055:Lipids / Q000097:blood; D008297:Male; D010949:Plasma / Q000378:metabolism*; D051381:Rats; D014810:Vitamin E / Q000097:blood*; D014811:Vitamin E Deficiency / Q000097:blood
chemical_list: D008055:Lipids; D014810:Vitamin E; D006493:Heparin