Isolation and characterization of surfactant-like particles in rat
and human colon.
Eliakim, Rami, George S. Goetz, Sandrine Rubio, Bernadette Chailley
-Heu, Jian-Su Shao, Robert Ducroc, and David H. Alpers.
WASHINGTON UNIVERSITY SCHOOL OF MEDICINE, DIVISION OF
GASTROENTEROLOGY, ST. LOUIS, MO, 63110 AND INSERM U.319,
UNIVERSIT[acute]e PARIS 7, PARIS, FRANCE
APStracts 3:0204G, 1996.
The source of a phospholipid-rich layer recovered from the surface of
the mammalian colon has been obscure. This report describes the
isolation of a low-density membrane from the surface of rat and human
colons (d=1.07-1.08 g/ml), with a low cholesterol/phospholipid ratio
and phosphatidylcholine as its major phospholipid. Electron
microscopy shows unilamellar and partially coiled membranes. Compared
with microvillous membranes isolated from underlying mucosa, this
extracellular membrane is enriched for tissue-unspecific alkaline
phosphatase and surfactant protein A. It does not contain small
intestinal marker proteins (intestinal alkaline phosphatase and
sucrase-isomaltase). The human membrane contains only traces of the
colonic microvillous membrane marker, carcinoembryonic antigen.
Antiserum against the rat colonic membrane does not recognize colonic
microvillous membrane or small intestinal surfactactant-like particle
proteins. Antiserum against human colonic membrane identifies one
protein in the surfactant-like particle from the adjacent small
intestine, and two proteins in the colonic microvillous membrane.
These data show that the colonocyte microvillous membrane is covered
by another membrane whose protein composition differs from it.
Enrichment for surfactant protein A suggests that this colonic
membrane is another example of a surfactant-like particle sharing
proteins with pulmonary surfactant.
Received 13 May 1996; accepted in final form 29 August 1996.
APS Manuscript Number G191-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996