Synthesis of phospholipids by human peritoneal mesothelial cells.
OBJECTIVE
To assess the capacity of cultured human peritoneal mesothelial cells to synthesize choline-containing phospholipids. The study compares the phospholipids secreted from cultured cells with those which we, and others, have identified in the dialysate of patients treated by continuous ambulatory peritoneal dialysis (CAPD).


METHODS
CAPD effluent was collected from 8 patients who had been receiving CAPD treatment for at least 11 months and who had normal ultrafiltration. CELL CULTURES: Using human omental tissue, homogeneous cultures of mesothelial cells were established.


METHODS
Synthesis of phospholipids by mesothelial cells was assessed following incubation with [methyl-14C] choline chloride--a precursor capable of being incorporated into phosphatidylcholine (PtdCho) and sphingomyelin. Lipids from CAPD effluent, cultured cells, and cell medium were extracted in chloroform/methanol. Phospholipids were separated and identified by thin layer chromatography. Synthesis and secretion of PtdCho and other choline-containing lipids by the mesothelial cells were determined by beta scintillation counting of the appropriate bands, while the fatty acid composition of the phospholipids was ascertained by gas liquid chromatography.


RESULTS
Synthesis and secretion of PtdCho by mesothelial cells were observed during a 96-hour period. When maintained in medium replete with essential fatty acids, the fatty acid composition of the PtdCho synthesized by cultured mesothelial cells closely resembled that isolated from the peritoneal cavity.


CONCLUSIONS
The demonstration of phospholipid secretion from mesothelial cells, with a fatty acid composition similar to the phospholipids isolated from peritoneal dialysate, lends added support to the hypothesis that the mesothelial cells are the source of the peritoneal phospholipids. As such they offer a useful experimental system in which to study peritoneal phospholipid synthesis.
Beavis
J
J
Institute of Nephrology, University of Wales College of Medicine, Royal Infirmary, Cardiff, United Kingdom.
Harwood
J L
JL
Coles
G A
GA
Williams
J D
JD
D002478:Cells, Cultured; D004848:Epithelium / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis; D006801:Humans; D010531:Peritoneal Dialysis, Continuous Ambulatory; D010537:Peritoneum / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000096:biosynthesis / Q000737:chemistry; D010743:Phospholipids / Q000096:biosynthesis* / Q000737:chemistry
D005227:Fatty Acids; D010713:Phosphatidylcholines; D010743:Phospholipids