Document Detail


3-Isobutyl-1-methylxanthine (IBMX) affects potassium permeability in rat sensory neurones via pathways that are sensitive and insensitive to [Ca2+]in.
MedLine Citation:
PMID:  7491267     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effects of externally applied 3-isobutyl-1-methylxanthine (IBMX), in millimolar concentrations, on the membrane currents in dorsal root ganglia (DRG) neurones isolated from newborn rats were investigated using the amphotericin-based "perforated" patch-clamp technique. In some experiments, simultaneous measurements of intracellular Ca2+ concentration ([Ca2+]in) were performed using fura-2 microfluorimetry. Applications of IBMX induced elevation of [Ca2+]in resulting from Ca2+ release from caffeine-ryanodine-sensitive internal stores. In addition to Ca2+ release, IBMX produced a biphasic membrane current response comprised of an inward current transiently interrupted by outward current. The onset of the inward current slightly preceded the onset of the [Ca2+]in transient, while the interrupting outward current developed synchronously with the [Ca2+]in rise. The development of IBMX-induced outward current ultimately needed the [Ca2+]in elevation. After the depletion of Ca2+ stores by IBMX or caffeine exposure, the subsequent IBMX challenge failed to produce both the [Ca2+]in transient and outward membrane current, although the inward current remained unchanged. Both components of the IBMX-induced membrane current response had a reversal potential close to the K+ equilibrium potential and the IBMX-induced membrane current response disappeared while dialysing the cell interior with K(+)-free, Cs(+)-containing solutions suggesting their association with K+ channel activity. External administration of 10 mM tetraethylammonium chloride (TEA-Cl) evoked an inward current similar to that observed in response to IBMX; in the presence of TEA-Cl, IBMX application was almost unable to induce additional inward current. IBMX (5 mM) effectively (approximately 50%) inhibited K+ currents evoked by step depolarizations of membrane potential.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
Y Usachev; P Kostyuk; A Verkhratsky
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  430     ISSN:  0031-6768     ISO Abbreviation:  Pflugers Arch.     Publication Date:  1995 Jul 
Date Detail:
Created Date:  1996-01-04     Completed Date:  1996-01-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  420-8     Citation Subset:  IM    
Affiliation:
Department of General Physiology of the Nervous System, Bogomoletz Institute of Physiology, Kiev, Ukraine.
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MeSH Terms
Descriptor/Qualifier:
1-Methyl-3-isobutylxanthine / pharmacology*
Animals
Animals, Newborn
Caffeine / pharmacology
Calcium / pharmacology*
Calcium Channels / drug effects,  metabolism
Fura-2
Ganglia, Spinal / cytology,  drug effects,  metabolism
Neural Pathways / cytology,  drug effects,  metabolism
Neurons, Afferent / drug effects,  metabolism*
Patch-Clamp Techniques
Phosphodiesterase Inhibitors / pharmacology*
Potassium / metabolism*
Rats
Ryanodine / pharmacology
Chemical
Reg. No./Substance:
0/Calcium Channels; 0/Phosphodiesterase Inhibitors; 15662-33-6/Ryanodine; 28822-58-4/1-Methyl-3-isobutylxanthine; 58-08-2/Caffeine; 7440-09-7/Potassium; 7440-70-2/Calcium; 96314-98-6/Fura-2

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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