Somatostatin increases voltage-gated K+ currents in GH3 cells through activation of multiple somatostatin receptors

Yang, Seung-Kwon, Parkington, Helena C., Blake, Allan D., Keating, Damien J. and Chen, Chen (2005) Somatostatin increases voltage-gated K+ currents in GH3 cells through activation of multiple somatostatin receptors. Endocrinology, 146 11: 4975-4984. doi:10.1210/en.2005-0696


Author Yang, Seung-Kwon
Parkington, Helena C.
Blake, Allan D.
Keating, Damien J.
Chen, Chen
Title Somatostatin increases voltage-gated K+ currents in GH3 cells through activation of multiple somatostatin receptors
Formatted title
Somatostatin increases voltage-gated K+ currents in GH3 cells through activation of multiple somatostatin receptors
Journal name Endocrinology   Check publisher's open access policy
ISSN 0013-7227
1945-7170
Publication date 2005-11-01
Sub-type Article (original research)
DOI 10.1210/en.2005-0696
Volume 146
Issue 11
Start page 4975
End page 4984
Total pages 10
Place of publication Chevy Chase, MD, United States
Publisher The Endocrine Society
Language eng
Formatted abstract
The secretion of GH by somatotropes is inhibited by somatostatin (SRIF) through five specific membrane receptors (SSTRs). SRIF increases both transient outward (IA) and delayed rectifying (IK) K+ currents. We aim to clarify the subtype(s) of SSTRs involved in K+ current enhancement in GH3 somatotrope cells using specific SSTR subtype agonists. Expression of all five SSTRs was confirmed in GH3 cells by RT-PCR. Nystatin-perforated patch clamp was used to record voltage-gated K+ currents. We first established the presence of IA and IK type K+ currents in GH3 cells using different holding potentials (–40 or –70 mV) and specific blockers (4-aminopirimidine and tetraethylammonium chloride). SRIF (200 nM) increased the amplitude of both IA and IK in a fully reversible manner. Various concentrations of each specific SRTR agonist were tested on K+ currents to find the maximal effective concentration. Activation of SSTR2 and SSTR4 by their respective agonists, L-779,976 and L-803,087 (10 nM), increased K+ current amplitude without preference to IA or IK, and abolished any further increase by SRIF. Activation of SSTR1 and SSTR5 by their respective agonists, L-797,591 or L-817,818 (10 nM), increased K+ current amplitude, but SRIF evoked a further increase. The SSTR3 agonist L-797,778 (10 nM) did not affect the K+ currents or the response to SRIF. These results indicate that SSTR1, -2, -4, and -5 may all be involved in the enhancement of K+ currents by SRIF but that only the activation of SSTR2 or -4 results in the full activation of K+ current caused by SRIF.
Keyword Somatotropes
Somatostatin
Membrane receptors
SSTRs
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
ERA 2012 Admin Only
School of Biomedical Sciences Publications
 
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Created: Tue, 13 Jan 2009, 14:18:48 EST by Gina Velli on behalf of School of Biomedical Sciences