Lipid content of human and rat pancreas.
We analyzed the lipid composition of the human pancreas and performed a parallel study on rat pancreas. Some precautions were taken in order to keep the secretory zymogens as inactive precursors in both tissues. The lipid content of the human pancreas corresponded to 5.5% of the tissue wet weight, lower than that found in pancreas of two-month-old Wistar rats (10%). In man, triglycerides and phospholipids were found at comparable levels, respectively, 37 and 30 mg/g of pancreas wet weight, not far from the values of the rat pancreas. In human pancreas, phosphatidylcholines and lysophosphatidylcholines represented about 40% of the total phospholipid fraction, phosphatidylethanolamines and lysophosphatidylethanolamines 21%, and phosphatidylserines and -inositols were found equally represented with 7.5%. The total cholesterol content accounted for about 4.5% of the total lipids; only 30% was esterified. By comparison, in rat, total cholesterol represented 3.3% of lipids and 90% was esterified. The phospholipids in human pancreas contained high amounts of saturated fatty acids (92%) mainly stearic and palmitic, whereas triglycerides contained equal amounts of saturated and unsaturated fatty acids, principally represented by oleic and palmitic acids. In rats the phospholipids contained only 63% saturated fatty acids (palmitic and stearic) and triglycerides contained 61% unsaturated fatty acids (mainly oleic and linoleic). In terms of lipid composition, there is a greater similarity between human and rat pancreas than with other known pancreas, such as the guinea pig and the ox.