Isolation and characterization of surfactant-like particles in rat and human colon

Rami Eliakim, George S. Goetz, Sandrine Rubio, Bernadette Chailley-Heu, Jian Su Shao, Robert Ducroc, David H. Alpers*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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-to-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 surfactant-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 with a different protein composition. Enrichment for surfactant protein A suggests that this colonic membrane is another example of a surfactant-like particle sharing proteins with pulmonary surfactant.

Original languageEnglish
Pages (from-to)G425-G434
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number3 35-3
StatePublished - Mar 1997
Externally publishedYes


FundersFunder number
National Institute of Diabetes and Digestive and Kidney DiseasesR01DK014038


    • alkaline phosphatase
    • membrane
    • surfactant protein A


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