Referenced in: none

Automatically associated channels: Kir2.3

Title: Effect of extracellular K+ on the intracellular free Ca2+ concentration in leech glial cells and Retzius neurones.

Authors: P Hochstrate, C Piel, W R Schlue

Journal, date & volume: Brain Res., 1995 Oct 23 , 696, 231-41

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8574674

Abstract
The effects of extracellular K+ on the intracellular free Ca2+ concentration ([Ca2+]i) of neuropile glial cells and Retzius neurones in intact segmental ganglia of the leech Hirudo medicinalis were investigated by using iontophoretically injected fura-2. In both cell types, an elevation of the extracellular K+ concentration ([K+]o) caused an increase in [Ca2+]i, which was blocked by Co2+, Ni2+ and menthol, whereas nicardipine, flunarizine, omega-conotoxin GVIA and omega-agatoxin IVA were ineffective. In Ca(2+)-free solution, the K(+)-induced [Ca2+]i increase was largely suppressed in neuropile glial cells and completely abolished in Retzius neurones. The results indicate that the K(+)-induced [Ca2+]i increase was mainly due to Ca2+ influx through voltage-dependent Ca2+ channels. The Ca2+ channels of the two cell types were activated at different membrane potentials but at the same [K+]o. In both cell types, the recovery from a K(+)-induced [Ca2+]i increase was unaltered in Na(+)-free solution, indicating that active Ca2+ transport across the plasma membrane is mediated by Na(+)-independent mechanisms.