Comparative biochemistry and physiology. Part A, Physiology 1997-10-01

Comparative aspects of actions of a short-chain phospholipid on epithelial Na+ channels and tight junction conductance.

M Röpke, M A Unmack, N J Willumsen, O Frederiksen

Index: Comp. Biochem. Physiol. A. Physiol. 118(2) , 211-4, (1997)

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Abstract

Ion transport in both the frog skin (a high-resistance epithelium) and the rabbit nasal airway epithelium (a low-resistance epithelium) are dominated by electrogenic Na+ absorption via apical membrane amiloride-sensitive Na+ channels, and short-circuit current (ISC) is essentially a measure of Na+ absorption in both epithelia. In both epithelia, mucosal application of the short-chain phospholipid didecanoyl-L-alpha-phosphatidylcholine (DDPC) dose-dependently inhibited the amiloride-sensitive ISC and caused an initial decrease in epithelial conductance (Gt) followed by an increase in Gt to steady-state values above control level. The effects were reversible. It is concluded that DDPC (a) inhibits epithelial amiloride-sensitive Na+ channels and (b) induces an increase in paracellular tight junction conductance. These effects may involve changes in non-specific lipid-protein interactions at the cell membrane level.