Lymph esterases of the house mouse (Mus musculus)--I. Identification and possible origins of abdominal lymph esterases.

1. Abdominal lymph was obtained from Mus musculus by cannulation of the thoracic duct: lymph esterases were identified by polyacrylamide gel electrophoresis. Seven known esterases (ES-1, ES-2, ES-5, ES-27, SE-I, SE-II and SE-III) and a newly described activity (SE-IV) were demonstrated, all of which were also present in serum. 2. Electrophoretic staining intensities indicated that the lymph esterases were less concentrated than the corresponding activities in serum, with the single exception of ES-2. This finding was supported by quantitative immunoelectrophoresis of ES-1 and ES-2 (two allozymes each). 3. The jejunum appeared to be the origin of lymph ES-2 by a comparison of organ distribution of the allozymes ES-2B and ES-2D and by monitoring the re-appearance of ES-2 in several organs, serum and lymph after total inhibition in vivo by bis-p-nitrophenyl phosphate.

Lymph esterases of the house mouse (Mus musculus)--II. The role of esterase-2 in fat resorption.

1. Intralipid infusion into the duodenum of Mus musculus was accompanied by changes in lymph and serum concentrations of two esterase isozymes, ES-1 and ES-2. Whereas ES-1 levels declined in both lymph and serum, ES-2 levels increased 5-fold in lymph within 120 min, and fell to a plateau 3- to 4-fold the fasting level; serum levels of ES-2 increased continually. 2. The changes in lymph ES-2 concentrations were paralleled by lymph triglyceride concentration during Intralipid infusion. Genetically determined differences in the concentration of two allozymes, ES-2B and ES-2D, were reflected in differences in lymph triglyceride levels. The lymph triglyceride concentration was strongly correlated with approximately the cube root of the lymph ES-2 concentration for both allozymes. 3. The source of lymph ES-2 during fat resorption was probably an intracellular jejunal pool; serum ES-2 also re-entered the lymph but this fraction was not influenced by fat resorption. 4. Purified chylomicrons possessed no esterase activity; however, it was postulated that ES-2 plays an essential role in fat resorption and is extruded with the primary chylomicrons from the enterocyte.