[Abstract Title]. - Society for Neuroscience

Hippocampal astrocytes were electrophysiologically identified by the large resting K + currents
which dominated the current pattern of these cells beyond postnatal (p) day 3. These currents
were sensitive to Ba 2+ at submillimolar concentration but were not pH-sensitive up to a pH of
6.5. By using single cell RT-PCR, the subunit Kir4.1 was encountered in all cells while Kir5.1,
another glial Kir subunit that co-assembles with Kir4.1, was co-expressed scarcely. In some
cells, co-expression of Kir2 transcripts was detected. In Kir4.1-deficient mice, astrocytes were
almost devoid of Ba 2+ -sensitive currents and lacked negative resting potentials, suggesting that
Kir4.1 is mainly responsible for astroglial Kir currents in the hippocampus.
A developmental up-regulation of Kir4.1 expression was found both on the mRNA and protein
levels. Semi-quantitative real-time RT-PCR revealed a strong rise in the amount of Kir4.1
mRNA between the p3 and p10, both in tissue from the stratum radiatum of the CA1 region as
well as in single astrocytes. Quantification of grey levels of Kir4.1 tetramers in respect to the
loading control of b-actin by Western blot analysis showed a 13-fold increase of Kir4.1 protein
between p3 and p10. Electrophysiological analysis confirmed expression of Ba 2+ sensitive Kir
currents in p3 astrocytes, but the amplitudes per cell surface area amounted to only 25%
compared to astrocytes at p10. This increase in astroglial Kir4.1 channel density parallels a
significant drop of the extracellular volume fraction of the developing hippocampus, suggesting
an important role of Kir4.1 in extracellular K + buffering.
Disclosures: G. Seifert , None; C. Hartmann, None; D.K. Binder, None; K. Hüttmann,
None; A. Wyczynski, None; C. Steinhäuser, None.
Poster
242. Glial Neuronal Interactions: Glutamate and Calcium
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 242.2/H9
Topic: B.11.c. In vivo approaches
Support: NHMRC
Title: Role of ATP in memory formation
Authors: *D. N. BOWSER 1 , M. E. GIBBS 2 ;
1 Howard Florey Inst., Parkville, Australia; 2 Anatmoy and Cell Biol., Monash Univ., Melbourne,
Australia
Abstract: The nucleotide ATP is recognized as a neurotransmitter and amongst its various roles,
is involved in neural-glial interactions in the brain. It functions both as an extracellular signalling
molecule and as a gliotransmitter and it has been suggested to have a pivotal role in learning and