DOPAMINE MODULATES THE SLOW Ca2+-ACTIVATED K+ CURRENT IAHP VIA CYCLIC AMP-
DEPENDENT PROTEIN KINASE IN HIPPOCAMPAL NEURONS.
Pedarzani, Paola and Johan F. Storm.
Institute of Neurophysiology, University of Oslo, PB 1104 Blindern, N-0317
Oslo, Norway.
APStracts 2:0294N, 1995.
SUMMARY AND CONCLUSIONS
1. The effects of dopamine on the slow Ca2+-dependent K+ current (IAHP) and
spike frequency adaptation were studied by whole-cell voltage-clamp and sharp
microelectrode current-clamp recordings in rat CA1 pyramidal neurons in
hippocampal slices. 2. Dopamine suppressed IAHP in a dose-dependent manner,
under whole-cell voltage-clamp conditions. Similarly, under current-clamp
conditions, dopamine inhibited spike frequency adaptation and suppressed the
slow afterhyperpolarization. 3. The effect of dopamine on IAHP was mimicked by
a D1 receptor agonist and blocked by dopamine receptor antagonists only in a
minority of the cells. 4. Dopamine suppressed IAHP after blocking or
desensitizing the [beta] -adrenergic receptors and, hence, did not act by
cross-reacting with this receptor type. 5. The effects of dopamine on IAHP and
spike frequency adaptation were suppressed by blocking the cAMP-dependent
kinase (PKA) with Rp-cAMPS and, hence, are probably mediated by the activation
of this kinase. 6. We conclude that dopamine increases hippocampal neuron
excitability, like other monoamine neurotransmitters, by suppressing IAHP and
spike frequency adaptation, via cAMP and protein kinase A. The receptor type
mediating this effect of dopamine remains to be defined.
Received 11 May 1995; accepted in final form 20 September 1995.
APS Manuscript Number J320-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95