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PMID: 8271204 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S.

Whole-cell recordings of inwardly rectifying K+ currents activated by 5-HT1A receptors on dorsal raphe neurones of the adult rat.

The Journal of physiology ·Vol. 469 ·1993-09-00 ·Pages 387-405

Penington NJ, Kelly JS, Fox AP

Abstract

1. An inwardly rectifying K+ current activated by serotonin (5-HT) was recorded from acutely isolated adult dorsal raphe (DR) neurones using the whole-cell recording mode of the patch clamp technique. 2. The 5-HT-induced K+ current (I5-HT) was only visible at an [K+]0 > 5 mM and it was observed in 69% of the cells. 3. The reversal potential for I5-HT was close to the potassium equilibrium potential and was shifted by 51 mV per 10-fold change in [K+]0 indicating that I5-HT was carried predominantly by K+. The chord conductance of I5-HT at -90 mV was proportional to the external [K+] raised to a fractional power. 4. A dose-response relationship revealed that I5-HT was activated with an ED50 of 30 nM. Ba2+ (0.1 mM) blocked I5-HT completely. Spiperone reversibly antagonized the response to 5-HT and 8-OHDPAT (8-hydroxy-2-(di-n-propylamino)tetralin) mimicked the response indicating that the receptor activated was of the 5-HT1A subtype. 5. The response to 5-HT was largely prevented by in vitro pretreatment of the cells with pertussis toxin (PTX) indicating the involvement of a PTX-sensitive G-protein in the transduction mechanism. 6. cAMP and lipoxygenase metabolites, both implicated in the modulation of similar currents in other preparations, were found not to alter the effectiveness of 5-HT. 7. Glibenclamide and tolbutamide, blockers of the ATP-regulated K+ channel, did not reduce the effect of 5-HT in DR neurones. 8. These results show that in acutely isolated adult DR neurones 5-HT activates an inwardly rectifying K+ current and this involves a PTX-sensitive G-protein in the transduction pathway which may interact with the K+ channel directly.

MeSH Terms
8-Hydroxy-2-(di-n-propylamino)tetralin/pharmacology Animals Barium/pharmacology Cyclic AMP/pharmacology Electrophysiology Glyburide/pharmacology In Vitro Techniques Ion Channel Gating/drug effects Masoprocol/pharmacology Membrane Potentials/drug effects Neurons/drug effects,metabolism Pertussis Toxin Potassium/pharmacology Potassium Channels/drug effects Raphe Nuclei/cytology,drug effects,metabolism Rats Receptors, Serotonin/drug effects,metabolism Serotonin/metabolism,physiology Serotonin Antagonists/pharmacology Spiperone/pharmacology Tolbutamide/pharmacology Virulence Factors, Bordetella/pharmacology
Chemicals
Potassium Channels Receptors, Serotonin Serotonin Antagonists Virulence Factors, Bordetella Barium Serotonin Spiperone 8-Hydroxy-2-(di-n-propylamino)tetralin Masoprocol Tolbutamide Cyclic AMP Pertussis Toxin Potassium Glyburide
Authors & Affiliations
3 authors, click to expand affiliations / ORCID
Penington N J
Department of Pharmacological and Physiological Sciences, University of Chicago, IL 60637.
Kelly J S
Fox A P
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Article Info
Journal
The Journal of physiology
Abbr.
J Physiol
ISSN
0022-3751
DOI
10.1113/jphysiol.1993.sp019819
Published
1993-09-00
Pages
387-405
Language
English
Region
England
NLM ID
0266262
PMCID
PMC1143876
Subset
IM
Grants
Wellcome Trust · United Kingdom
External Links
PubMed source DOI: 10.1113/jphysiol.1993.sp019819 PMC Full Text View journal details
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