Block of native Ca(2+)-permeable AMPA receptors in rat brain by intracellular polyamines generates double rectification Journal Article


Author(s): Koh, Duk S; Burnashev, Nail A; Jonas, Peter
Article Title: Block of native Ca(2+)-permeable AMPA receptors in rat brain by intracellular polyamines generates double rectification
Affiliation
Abstract: 1. The influence of intracellular factors on current rectification of different subtypes of native α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs) was studied in rat brain slices by combining fast application of glutamate with patch pipette perfusion. 2. The peak current-voltage (I-V) relation of the AMPARs expressed in Bergmann glial cells of cerebellum and dentate gyrus (DG) basket cells of hippocampus was weakly rectifying in outside-out patches and nystatin-perforated vesicles, but showed a doubly rectifying shape with a region of reduced slope between 0 and +40 mV in nucleated patches. The I-V relation of AMPARs expressed in hippocampal CA3 pyramidal neurones was linear in all recording configurations. 3. Intracellular application of 2.5 μM spermine, a naturally occurring polyamine, blocked outward currents in outside-oat patches from Bergmann glial cells and DG basket cells in a voltage-dependent manner, generating I-V relations with a doubly rectifying shape which were similar to those recorded in nucleated patches. AMPARs in CA3 pyramidal cell patches were unaffected by 25 μM spermine. 4. The half-maximal blocking concentration of spermine at +40 mV was 0.3 μM in Bergmann glial cell patches and 1.5 μM in DG basket cell patches, whereas it was much higher (≥ 100 μM) for CA3 pyramidal. cell patches. Spermidine also affected current rectification, but with lower affinity. The block of outward current by polyamines following voltage jumps developed within < 0.5 ms. 5. We conclude that current rectification, rather than being an intrinsic property of the Ca2+ permeable AMPAR channel, is generated by polyamine block.
Keywords: Rats; Electrophysiology; Kinetics; Brain; Calcium; Patch-Clamp Techniques; Rats, Wistar; Permeability; animal; Receptors, AMPA; Intracellular Membranes; Polyamines
Journal Title: Journal of Physiology
Volume: 486
Issue Pt 2
ISSN: 1469-7793
Publisher: Wiley-Blackwell  
Date Published: 1995-07-15
Start Page: 305
End Page: 312
URL:
DOI: 10.1113/jphysiol.1995.sp020813
Open access: yes (repository)