Characteristics and physiological role of surfactant-like particles secreted by entrocytes.
Intestinal epithelium secretes novel unilamellar membranes having characteristics similar to lung surfactants and thus has been named Surfactant-like particles (SLP). The chemical analysis of the membranes revealed cholesterol/phospholipid molar ratio of 0.68-0.78, which is much distinct from that of the underlying microvillus membranes (1.34-1.49). The membrane contains 4-6 proteins with a molar weight of 30-120 kDa and is enriched with alkaline phosphatase, contains low amounts of disaccharidases but no Na+, K(+)-ATPase activity. The secretion of SLP is stimulated by fat feeding. Chronic ethanol ingestion also induces the formation of SLP in rat intestine. A number of physiological functions have been attributed to SLP, which include: (i) as a protective lubricant in intestinal lumen, (ii) a role in triacylglycerol transport, (iii) as a vehicle for the transport of luminal proteins into blood, (iv) as a stratum for the adhesion of microorganisms in intestinal lumen, and (v) a role in trans-signalling mechanism across the basolateral surface of enterocytes.
Turan
Aasma
A
Department of Biochemistry, Panjab University, Chandigarh 160 014, India.
Gupta
Shiffalli
S
Mahmood
Akhtar
A
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology; D020895:Enterocytes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism / Q000502:physiology*; D008074:Lipoproteins / Q000378:metabolism / Q000502:physiology*; D010743:Phospholipids / Q000378:metabolism / Q000502:physiology*; D013501:Surface-Active Agents
D004041:Dietary Fats; D008074:Lipoproteins; D010743:Phospholipids; D013501:Surface-Active Agents; D000469:Alkaline Phosphatase