Referenced in: none

Automatically associated channels: Kir2.3

Title: Mechanism of Cl- sensitivity in internal ion receptors of the leech: an inward current gated off by Cl- in the nephridial nerve cells.

Authors: A Wenning, R L Calabrese

Journal, date & volume: J. Comp. Physiol. A, 1991 Jan , 168, 53-61

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/2033568

Abstract
The nephridial nerve cells of the leech, Hirudo medicinalis, 34 sensory cells, each associated with one nephridium, are sensitive to changes in extracellular Cl- concentration, an important factor in ion homeostasis. Using single-electrode current- and voltage clamp and ion substitution techniques, the specificity and mechanism of Cl- sensitivity of the nephridial nerve cell was studied in isolated preparations. Increase of the normally low external Cl- concentration leads to immediate and sustained hyperpolarization, decrease of the frequency of bursts and decrease of membrane conductance. The response is halogen specific: Cl- can be replaced by Br-, but not by organic mono- or divalent anions or inorganic divalent anions. At physiological Cl- concentrations (36 mM extracellular Cl-), the nephridial nerve cell has a high resting conductance for Cl- and the membrane potential is governed by Cl-. In high extracellular Cl- concentrations (110-130 mM), membrane conductance is low, most likely due to the gating off of Cl- channels. Under these conditions, membrane potential is dominated by the K+ distribution and the nephridial nerve cell hyperpolarizes towards EK.