title: The composition of plasma lipoproteins and erythrocyte membranes in cholesterol-fed pigs with partial ileal bypass.
abstract: The composition of plasma lipoproteins and erythrocyte membranes was studied in cholesterol-fed pigs with a partial ileal bypass. Cholesterol feeding caused marked increases in the plasma concentrations of cholesterol and phospholipids. In spite of continuation of cholesterol feeding, PIB reduced plasma concentrations of cholesterol and phospholipids towards basal values. PIB completely counteracted the dietary cholesterol induced alterations in the lipid composition of the apoprotein B containing plasma lipoproteins, but not in the HDL2 fraction. It is suggested that PIB specifically influences the metabolism of the atherogenic, apoprotein B containing lipoproteins. Dietary cholesterol caused significant increases in the ratios of cholesterol:phospholipids and phosphatidylcholine: sphingomyelin in erythrocytes. The high-cholesterol diet also increased the content of linoleic acid in erythrocyte phosphatidylcholine. PIB completely nullified the cholesterol-induced increase in the cholesterol:phospholipid ratio, but not the increase in the phosphatidylcholine:sphingomyelin ratio. The percentage of linoleic acid in erythrocyte phosphatidylcholine was unaffected by PIB. Neither cholesterol feeding nor PIB had an effect on the lipid fluidity of erythrocyte membranes, as measured by fluorescence polarization, using the probe diphenylhexatriene. Possible compensatory mechanisms operating to control homeostasis of lipid fluidity of erythrocyte membranes are discussed.
mesh_terms: D000818:Animals; D001835:Body Weight; D002791:Cholesterol, Dietary / Q000008:administration & dosage*; D004910:Erythrocyte Membrane / Q000032:analysis*; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D007581:Jejunoileal Bypass; D008074:Lipoproteins / Q000097:blood*; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D010713:Phosphatidylcholines / Q000097:blood; D010743:Phospholipids / Q000097:blood; D013552:Swine; D014280:Triglycerides / Q000097:blood
chemical_list: D002791:Cholesterol, Dietary; D006454:Hemoglobins; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D010713:Phosphatidylcholines; D010743:Phospholipids; D014280:Triglycerides