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.

Gastric mucosal phospholipids in dogs with familial stomatocytosis-hypertrophic gastritis.

In dogs, hypertrophic gastritis, which resembles Ménétrier's disease in man, has been demonstrated to be part of a hereditary syndrome called familial stomatocytosis-hypertrophic gastritis. In addition to hypertrophic gastritis, affected dogs exhibit abnormal blood phospholipid composition. Phospholipids may play a role in maintaining gastric mucosal integrity, and this may be compromised in gastritis. The question arises whether the differences in blood phospholipids may result from a disorder that might also be revealed in the composition of gastric mucosal phospholipids. We analysed the phospholipid composition of gastric mucosa from four dogs with familial stomatocytosis-hypertrophic gastritis. The general phospholipid composition and the molecular composition of phosphatidylcholine from mucosal tissue in the corpus of the stomach where hypertrophic gastritis was evident were not different from that of the antrum, where the tissue was normal. These results do not corroborate a relation between the gastric mucosal phospholipid composition and hypertrophic gastritis.