Journal article
3-Isobutyl-1-methylxanthine (IBMX) affects potassium permeability in rat sensory neurones via pathways that are sensitive and insensitive to [Ca2+]in
Pflügers Archiv, Vol.430(3), pp.420-428
07/1995
DOI: 10.1007/BF00373918
PMID: 7491267
Abstract
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)
Details
- Title: Subtitle
- 3-Isobutyl-1-methylxanthine (IBMX) affects potassium permeability in rat sensory neurones via pathways that are sensitive and insensitive to [Ca2+]in
- Creators
- Yuri UsachevPlaton KostyukAlexej Verkhratsky
- Resource Type
- Journal article
- Publication Details
- Pflügers Archiv, Vol.430(3), pp.420-428
- DOI
- 10.1007/BF00373918
- PMID
- 7491267
- ISSN
- 0031-6768
- eISSN
- 1432-2013
- Language
- English
- Date published
- 07/1995
- Academic Unit
- Iowa Neuroscience Institute; Anesthesia; Fraternal Order of Eagles Diabetes Research Center; Neuroscience and Pharmacology
- Record Identifier
- 9984040309802771
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