Neurophysiology

, Volume 19, Issue 6, pp 535–540 | Cite as

Depolarizing effects of dopamine on the primary afferent fibers of a segment isolated from the spinal cord of newborn rats

  • V. N. Oksamitnyi
  • Z. A. Tamarova
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Abstract

Effects of dopamine on dorsal root potentials were investigated during experiments on a segment of spinal cord isolated from 12- to 18-day-old rats. Applying dopamine to the brain was found to produce a slow, reversible, dose-dependent depolarization at primary afferent fiber terminals. This dopamine-induced depolarization was retained during complete blockade of synaptic transmission brought about by exchanging calcium ions in the perfusing fluid by magnesium or manganese ions. Minimum dopamine concentration required to produce this effect was 1·10−10–1·10−9 M. Peak amplitude of depolarization equaled 1.5 mV. Duration of this reaction ranged from 5.5 to 36.7 min, depending on the duration and concentration of dopamine application. Depolarizing response to dopamine differed considerably from GABA-induced dorsal root depolarization in amplitude and rate of rise. Haloperidol, a dopamine antagonist, reduced dopamine-induced dorsal root depolarization. Findings indicate that dopamine acts directly on the membrane of primary afferent fiber terminals, shifting membrane potential toward depolarization. This raises the possibility that dopaminergic brainstem-spinal pathways may exert an effect on sensory information transmission in segmental reflex arcs already traveling to the spinal cord.

Keywords

Spinal Cord Dopamine Haloperidol Information Transmission Dopamine Concentration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Plenum Publishing Corporation 1988

Authors and Affiliations

  • V. N. Oksamitnyi
  • Z. A. Tamarova

There are no affiliations available

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