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Title: Isolation and characterization of a mucosal triacylglycerol pool undergoing hydrolysis

Abstract

Absorbed and processed mucosal neutral lipid has been shown to be composed of at least two pools of triacylglycerol. One is likely to subserve chylomicron formation, and the other appears to be transported from the intestine via a nonlymphatic route. In the present study, 50 +/- 5% of the mucosal lipid pellets was centrifuged at 75,000 g.min (low-speed pellet (LSP)). Discontinuous sucrose density gradient centrifugation of LSP showed that 61 +/- 7% of the lipid banded at the 0.25-0.86 M sucrose interface. Neutral lipid analysis showed that this subfraction was only 58% triacylglycerol, suggesting it was undergoing hydrolysis. Active lipolytic activity in vitro was found on incubation. The lipase had an alkaline pH optimum (pH 8.5) and persisted despite pancreatic ductular diversion. Lipolysis in vivo in a LSP fraction was shown by infusing (14C)glyceryltrioleate for 3.5 h followed by (3H)glyceryltrioleate for 30 min. Discontinuous sucrose density centrifugation of the LSP followed by an analysis of the lipids at the 0.25-0.86 M sucrose interface showed that 14C-neutral lipids were only 70 +/- 6% triacylglycerol, whereas 3H-neutral lipids were 88 +/- 2% triacylglycerol. 3H entered LSP slowly compared with the floating lipid in the same centrifuge tube. These studies suggest both inmore » vivo and in vitro mucosal lipolysis by a specific, alkaline-active lipase. The turnover rate of LSP is likely to be slow by comparison with neutral lipid floating to the top of the centrifuge tube.« less

Authors:
; ;  [1]
  1. (Univ. of Tennessee, Memphis (USA))
Publication Date:
OSTI Identifier:
6968774
Resource Type:
Journal Article
Resource Relation:
Journal Name: American Journal of Physiology; (USA); Journal Volume: 257
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; LIPIDS; CHEMICAL COMPOSITION; CARBON 14 COMPOUNDS; CHOLESTEROL; ELECTRON MICROSCOPY; IN VITRO; IN VIVO; INTESTINES; ISOTOPE DILUTION; LIPASES; METABOLISM; MUCOUS MEMBRANES; RATS; TRIGLYCERIDES; TRITIUM COMPOUNDS; ULTRACENTRIFUGATION; ANIMALS; BODY; CARBOXYLESTERASES; CENTRIFUGATION; DIGESTIVE SYSTEM; ENZYMES; ESTERASES; ESTERS; GASTROINTESTINAL TRACT; HYDROGEN COMPOUNDS; HYDROLASES; HYDROXY COMPOUNDS; ISOTOPE APPLICATIONS; LABELLED COMPOUNDS; MAMMALS; MEMBRANES; MICROSCOPY; ORGANIC COMPOUNDS; ORGANS; RODENTS; SEPARATION PROCESSES; STEROIDS; STEROLS; TRACER TECHNIQUES; VERTEBRATES; 550201* - Biochemistry- Tracer Techniques; 550501 - Metabolism- Tracer Techniques

Citation Formats

Tipton AD IV, Frase, S., and Mansbach, C.M. II. Isolation and characterization of a mucosal triacylglycerol pool undergoing hydrolysis. United States: N. p., 1989. Web.
Tipton AD IV, Frase, S., & Mansbach, C.M. II. Isolation and characterization of a mucosal triacylglycerol pool undergoing hydrolysis. United States.
Tipton AD IV, Frase, S., and Mansbach, C.M. II. Fri . "Isolation and characterization of a mucosal triacylglycerol pool undergoing hydrolysis". United States. doi:.
@article{osti_6968774,
title = {Isolation and characterization of a mucosal triacylglycerol pool undergoing hydrolysis},
author = {Tipton AD IV and Frase, S. and Mansbach, C.M. II},
abstractNote = {Absorbed and processed mucosal neutral lipid has been shown to be composed of at least two pools of triacylglycerol. One is likely to subserve chylomicron formation, and the other appears to be transported from the intestine via a nonlymphatic route. In the present study, 50 +/- 5% of the mucosal lipid pellets was centrifuged at 75,000 g.min (low-speed pellet (LSP)). Discontinuous sucrose density gradient centrifugation of LSP showed that 61 +/- 7% of the lipid banded at the 0.25-0.86 M sucrose interface. Neutral lipid analysis showed that this subfraction was only 58% triacylglycerol, suggesting it was undergoing hydrolysis. Active lipolytic activity in vitro was found on incubation. The lipase had an alkaline pH optimum (pH 8.5) and persisted despite pancreatic ductular diversion. Lipolysis in vivo in a LSP fraction was shown by infusing (14C)glyceryltrioleate for 3.5 h followed by (3H)glyceryltrioleate for 30 min. Discontinuous sucrose density centrifugation of the LSP followed by an analysis of the lipids at the 0.25-0.86 M sucrose interface showed that 14C-neutral lipids were only 70 +/- 6% triacylglycerol, whereas 3H-neutral lipids were 88 +/- 2% triacylglycerol. 3H entered LSP slowly compared with the floating lipid in the same centrifuge tube. These studies suggest both in vivo and in vitro mucosal lipolysis by a specific, alkaline-active lipase. The turnover rate of LSP is likely to be slow by comparison with neutral lipid floating to the top of the centrifuge tube.},
doi = {},
journal = {American Journal of Physiology; (USA)},
number = ,
volume = 257,
place = {United States},
year = {Fri Dec 01 00:00:00 EST 1989},
month = {Fri Dec 01 00:00:00 EST 1989}
}