Aspects of phospholipid metabolism in liver and intestine

[摘要] Few results have been published about the composition of individual phospholipids in liver cell nuclei. Nuclei have been isolated in either 1% citric acid or 2.2M sucrose. Rigorous tests by chemical and microscopic methods showed them to be virtually free from contamination. The chemical composition of these nuclei has been compared. Evidence from lipid analyses, surface area measurements of lipid films, and electron microscopy is consistent with the view that citric acid-isolated nuclei are bounded by a single unit-membrane, whereas in sucrose-isolated nuclei the typical double membrane is preserved. The composition of glycerophosphatides in various tissues has been measured by paper chromatography of their water-soluble deacylation products. Both phospholipids and fatty acids are similarly distributed in nuclear, mitochondrial and microsomal fractions of rat liver. Only cardiolipin seems to have a unique site in the cell - namely in the mitochondrion. A survey of various tissues indicated that a particular phospholipid pattern is fairly widespread. The 32P uptake by phospholipids of rat liver cell fractions has been studied at different times in vivo. Whereas large differences have been observed in the uptake of label by individual phospholipids, the pattern of labelling is similar in each cell fraction. There was no significant change in the uptake of 32P into phospholipids of regenerating liver over normal or sham-operated controls in any cell fraction under the conditions chosen for investigation. No specific phospholipid appeared to be concerned in cell division. In the intestinal mucosa of the rat, phosphatidic acid was the most highly labelled phospholipid after a thirty minute isotopic exchange period. During the absorption of triglyceride, the labelling of this compound did not change significantly, but the uptake of isotope into phosphatidylcholine increased five-fold. This was probably due to the increased requirement of phosphatidylcholine for stabilisation of the chylomicrons during fat absorption.

[发布机构] University:University of Birmingham;Department:Department of Medical Biochemistry and Pharmacology

[关键词] Q Science;QP Physiology