Bidirectional regulation of neuronal potassium. Currents by the G-protein activator aluminum fluoride as a function of intracellular calcium concentration

L. D. Matzel, R. F. Rogers, A. C. Talk

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Hydrolysis-resistant activation of G-proteins by extracellular perfusion of fluoride ions was examined in Type B cells isolated from the cerebral ganglion of the marine mollusc Hermissenda. Under single-electrode voltage-clamp, modulation by aluminum fluoride ions of several classes of outward K+ currents as well as an inward Ca2+ current was observed. Following injection of the Ca2+ chelator EGTA, aluminum fluoride ions selectively increased a slow, voltage-dependent K+ current (I(K) within 5 min of application, while in the absence of EGTA, aluminum fluoride ions induced a small, transient reduction of I(K). Neither the magnitude nor steady-state inactivation of a fast, voltage-dependent K+ current (I(A)), nor a slow, Ca2+-dependent K+ current (I(K-Ca)), were affected by aluminum fluoride ions. In contrast, when perfusion of aluminum fluoride ions was accompanied by a repetitive depolarization and a concomitant increase in intracellular Ca2+, both I(A) and the combined late currents (I(K) and I(K-Ca)) were markedly reduced, a reduction which was not observed following depolarization alone or if the pairing of aluminum fluoride ions and depolarization was preceded by an injection of EGTA. The reduction of membrane conductance by the pairing of aluminum fluoride ions with depolarization could not be accounted for by an increased Ca2+ conductance, as aluminum fluoride ions produced only a small decrease in the voltage-dependent Ca2+ current. In total, these results indicate that regulatory G-proteins may bidirectionally modulate neuronal K+ currents, the direction of which is dependent on intracellular Ca2+ concentration. Such a dual regulatory mechanism may contribute to the modulation of membrane excitability observed when presynaptic activity is paired with postsynaptic depolarization, and thus may contribute to some forms of activity-dependent plasticity involving metabatropic receptors.

Original languageEnglish (US)
Pages (from-to)1175-1185
Number of pages11
JournalNeuroscience
Volume74
Issue number4
DOIs
StatePublished - Oct 1996

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Keywords

  • Activity-dependent facilitation
  • Calcium
  • Fluoride
  • G-proteins
  • Hermissenda
  • Potassium currents

Fingerprint Dive into the research topics of 'Bidirectional regulation of neuronal potassium. Currents by the G-protein activator aluminum fluoride as a function of intracellular calcium concentration'. Together they form a unique fingerprint.

Cite this