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5‐Hydroxytryptamine activates a barium‐sensitive, cAMP‐mediated potassium conductance in the leech giant glial cell
Author(s) -
Britz Frank C.,
Hirth Ingolf C.,
Schneider HansPeter,
Deitmer Joachim W.
Publication year - 2005
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.20120
Subject(s) - biology , hirudo medicinalis , neuropil , neurotransmitter , leech , serotonergic , neuroglia , neuroscience , adenylyl cyclase , extracellular , 5 ht receptor , biophysics , serotonin , microbiology and biotechnology , receptor , central nervous system , biochemistry , stimulation , world wide web , computer science
5‐Hydroxytryptamine (5‐HT), a neurotransmitter and neuromodulator in the central nervous system of the leech Hirudo medicinalis hyperpolarizes the giant glial cell in the neuropil of segmental ganglia at micromolar concentrations. The 5‐HT‐evoked glial response (EC 50 ≈2.5 μM) is mediated by a non–desensitizing, G‐protein‐coupled receptor and due to activation of a Ca 2+ ‐independent K + conductance. The adenylyl cyclase inhibitor SQ22,536 blocks the response to 5‐HT; in the presence of 1 mM db‐cAMP, but not of 1 mM db‐cGMP, the glial response is suppressed. The 5‐HT‐evoked response is reduced by Ba 2+ with half‐maximal inhibition at 50 μM Ba 2+ . The results suggest that release of 5‐HT from serotonergic neurons, or the maintenance of micromolar levels of extracellular 5‐HT in the ganglion, may help to set the glial membrane potential close to the K + equilibrium potential. © 2004 Wiley‐Liss, Inc.