The K+-induced increases in noradrenaline and dopamine release are accompanied by reductions in the release of their intraneuronal metabolites from the rat anterior hypothalamus: An in vivo brain microdialysis study

E. Badoer, H. Würth, D. Türek, F. Qadri, K. Itoi, P. Dominiak, Th Unger

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)

Abstract

The novel technique of microdialysis has been used to examine the basal and K+-induced release of catecholamines and metabolites from the anterior hypothalamus of the urethane-anaesthetized rat in vivo. A high pressure liquid chromatographic assay was developed to simultaneously measure endogenous noradrenaline, dopamine and their intraneuronal metabolites 3,4-dihydroxyphenylglycol (DOPEG) and 3,4-dihydroxyphenylacetic acid (DOPAC) respectively, in each 60 μl dialysate sample. The effect of replacing Ca2+ in the perfusion fluid with a low concentration of Cd2+, which blocks Ca2+ effects, was also studied. Increasing the K+ concentration in the perfusion fluid elicited a concentration-dependent increase in noradrenaline and dopamine release. In contrast, there were marked reductions in DOPEG and DOPAC which were not concentration-dependent. In the Ca2+-depleted conditions, the K+-induced increase in amine release was significantly attenuated, but the reductions in the metabolites were not affected. We suggest that the mechanisms contributing to the observed reductions in the metabolites may be inhibition of neuronal reuptake, an increase in neuronal efflux, an enhancement of vesicular uptake and a decrease in vesicular efflux.

Original languageEnglish
Pages (from-to)54-59
Number of pages6
JournalNaunyn-Schmiedeberg's Archives of Pharmacology
Volume339
Issue number1
DOIs
Publication statusPublished - 1989 Jan
Externally publishedYes

Keywords

  • 3,4-Dihydroxyphenylacetic acid
  • 3,4-Dihydroxyphenylglycol
  • Anterior hypothalamus
  • Brain microdialysis
  • Dopamine
  • Noradrenaline

ASJC Scopus subject areas

  • Pharmacology

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