Studies on the Specificity and Behavior of Blood and Tissue Lipases.

Abstract

It has long been known that the lipase normally present in the blood will not split true fats, 1 and that the pancreas contains much greater amounts of a true fat-splitting lipase than do any other organs. A search of the literature has failed to reveal any report of the appearance in the blood of a fat-splitting lipase in experimental pancreatic injury, although it is well known that such injury increases the blood diastase.

We have studied the blood lipases of 5 dogs with experimental pancreatic injury; in one of these animals, the pancreatic ducts were ligated, in one the tail of the pancreas was doubly ligated and severed from the body, and in the remaining 3 the body of the pancreas was removed, leaving the head and tail free in the mesentery. The blood lipases were followed in these animals, using olive oil and ethyl butyrate as substrates. In making determinations on olive oil a 50% emulsion of the oil previously freed from fatty acid and containing 5% of acacia as an emulsifying agent and 0.2% of sodium benzoate as a preservative was used. One cc. of serum, 2 cc. of the olive oil emulsion, 3 cc. of distilled water, and 0.5 cc. of a normal phosphate buffer adjusted to pH 7.0 were shaken together and incubated at 40°C. for 24 hours. For ethyl butyrate determinations, 1 cc. of ethyl butyrate (absolute) was substituted for the olive oil emulsion. After incubation 3 cc. of 95% alcohol and 3 drops of 1% phenolphthalein were added and the mixture titrated with N/20 acid to a faint pink. Controls containing 1 cc. of serum inactivated by heat were run simultaneously. A lipase capable of hydrolyzing olive oil appeared in the blood of all animals very promptly, the highest values observed being attained within 24 hours.