Referenced in: none

Automatically associated channels: Kir2.3

Title: Characterization of a voltage-dependent conductance in the basolateral membrane of leech skin epithelium.

Authors: M Schnizler, W Clauss

Journal, date & volume: J. Comp. Physiol. B, Biochem. Syst. Environ. Physiol., 1998 May , 168, 295-302

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/9646506

Abstract
Voltage clamp studies were performed on the dorsal integument of Hirudo medicinalis. Under apical calcium-free conditions an inward-directed component of transepithelial current was activated by changes of transepithelial voltage. Depolarization caused up to 50% increase of the transepithelial sodium current. Hyperpolarization had no comparable effects. With calcium (1.8 mM) or amiloride (100 microM) in the apical solution and in sodium-free solutions the inward-directed current failed to increase after depolarization. Activation also occurred under chloride-free conditions. Permeabilization of the apical membrane by nystatin (5 microM) increased the current activation significantly. After nystatin, calcium as well as amiloride lost their inhibitory effects. This indicates a basolateral localization of the voltage-dependent conductance. Vesicle insertion or cytoskeletal structures are probably not involved in regulation, as seen by the lack of effects of brefeldin A and the cytochalasins B and D. However, serosal hyposmolar solutions (170 mosmol.1(-1)) caused a reinforced activation of the current. Our results indicate a voltage-dependent conductance in a tight sodium-absorbing epithelium.