Membrane lipid composition and susceptibility to bile salt damage.
Erythrocyte membranes with low sphingomyelin : choline-containing phospholipid ratios haemolyse at low concentrations of the bile salt, glycocholate. Erythrocytes with higher sphingomyelin : choline-containing phospholipid ratios require progressively greater concentrations of the bile salt for lysis. Sublytic concentrations of glycocholate remove phospholipid and acetylcholinesterase from the membranes. Membranes with low sphingomyelin : choline-containing phospholipid ratios lose both particulate (microvesicles of distinct composition) and 'solubilized' material, the particulate form predominating. The proportion of particulate material falls with increase of the membrane sphingomyelin : choline-containing phospholipid ratio and those membranes of highest sphingomyelin : choline-containing phospholipid ratio lose material predominantly in 'solubilized' form. Sheep erythrocytes treated to increase their content of phosphatidylcholine (and thereby reduce their membrane sphingomyelin : choline-containing phospholipid ratio) become more susceptible to lysis by glycocholate. These observations indicate a correlation between membrane lipid composition and the perturbation of membranes with bile salt; they also point to possible features of membranes capable of surviving exposure to the high bile salt concentrations of the biliary tract.
D000818:Animals; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006000:Glycocholic Acid / Q000494:pharmacology*; D006168:Guinea Pigs; D006461:Hemolysis; D006801:Humans; D008563:Membrane Lipids / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism*; D012756:Sheep / Q000097:blood; D013045:Species Specificity; D013109:Sphingomyelins / Q000378:metabolism*
D008563:Membrane Lipids; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D006000:Glycocholic Acid