Parallel secretion of pancreatic phospholipase A(2), phospholipase A(1), lipase, and colipase in children with exocrine pancreatic dysfunction

The cosecretion of pancreatic lipase and colipase are important in normal f at digestion. As adsorption of phosphatidylcholine to the lipid substrate i nterferes with lipase activity, hydrolysis to lysophosphatidylcholine with subsequent desorption is also essential for fat digestion. Then are some da ta regarding the secretion of pancreatic phospholipases in normal adults bu t none in children or patients with pancreatic disease. In the present stud y, we aimed a) to develop an accurate fast assay method to measure phosphol ipase A(2) and b) to determine the secretion rate of pancreatic phospholipa se A(2) and whether it is cosecreted with lipase and colipase in children w ith exocrine pancreatic dysfunction. Nine male patients aged 0.5 to 16 y (s even with cystic fibrosis, two with malabsorption) underwent pancreatic sti mulation tests. Their colipase and lipase secretion rates were measured by titrimetric methods and phospholipase A(2) and A(1) by phosphorus magnetic resonance spectroscopy (P-31 NMR). It was found that the phospholipases, co lipase, and lipase were absent in the two patients with pancreatic insuffic iency. In patients with normal absorption, there were marked inter-and intr asubject variations of lipase, colipase, and phospholipase secretion rates that were consistent with the degree of exocrine pancreatic dysfunction. Ho wever, in the three 20-min stimulation periods of the pancreatic function t est, pancreatic phospholipase is cosecreted with lipase and colipase, and a verage colipase and phospholipase A(2) secretion rates follow a similar or parallel pattern. These findings are consistent with the important role of pancreatic phospholipases in intestinal phospholipid hydrolysis leading to the desorption of phospholipids from the lipid substrate and enhancing lipi d hydrolysis and phospholipid absorption.