Quantifying vesicle/mixed micelle partitioning of phosphatidylcholine in model bile by using radiolabeled phosphatidylcholine species.
Phospholipid in vesicles and mixed micelles of (model) bile has been traced or quantitated (or both) by adding radioactively labeled phosphatidylcholine species. The question is whether these labeled species mix homogeneously with the phosphatidylcholine species mixture present, such that the label distribution reflects the already established mass partitioning of species. In this study, model bile containing egg yolk phosphatidylcholine was incubated with radioactive phosphatidylcholine species. Vesicle and mixed micelle fractions were separated by gel filtration. Radiochemical analysis of the species distribution confirmed chemical analysis: 1,2-di(14C)palmitoyl-phosphatidylcholine was enriched in the vesicles, the 1-palmitoyl-2-(14C)oleoyl species evenly distributed, and the 1-palmitoyl-2-(14C)linoleoyl species more expressed in mixed micelles. This indicates that the distribution of an added radioactive phosphatidylcholine species represents the vesicle/mixed micelle distribution of that particular phosphatidylcholine species. Consequently, the label distribution of a particular added radioactive phosphatidylcholine species can be used to calculate the vesicle/mixed micelle partitioning of total phosphatidylcholine only after it has been established that the radioactive species reaches the same partitioning as total phosphatidylcholine.
Renooij
W
W
Department of Surgery, University Hospital Utrecht, The Netherlands.
van Gaal
P J
PJ
van Erpecum
K J
KJ
van de Heijning
B J
BJ
van Berge Henegouwen
G P
GP
D001646:Bile / Q000737:chemistry*; D002250:Carbon Radioisotopes; D002850:Chromatography, Gel / Q000379:methods; D008823:Micelles; D010713:Phosphatidylcholines / Q000737:chemistry*; D012995:Solubility
D002250:Carbon Radioisotopes; D008823:Micelles; D010713:Phosphatidylcholines