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Experimental Brain Research

, Volume 101, Issue 2, pp 265–271 | Cite as

Influence of acid-base changes on the intracellular calcium concentration of neurons in primary culture

  • Y. B. OuYang
  • P. Mellergård
  • T. Kristián
  • V. Kristiánova
  • B. K. Siesjö
Original Paper

Abstract

The influence of changes in intra- and extracellular pH (pHi and pHe, respectively) on the cytosolic, free calcium concentration ([Ca2+]i) of neocortical neurons was studied by microspectrofluorometric techniques and the fluorophore fura-2. When, at constant pHe, pHi was lowered with the NH4Cl prepulse technique, or by a transient increase in CO2 tension, [Ca2+]i invariably increased, the magnitude of the rise being proportional to ΔpHi. Since similar results were obtained in Ca2+-free solutions, the results suggest that the rise in [Ca2+]i was due to calcium release from intracellular stores. The initial alkaline transient during NH4Cl exposure was associated with a rise in [Ca2+]i. However, this rise seemed to reflect influx of Ca2+ from the external solution. Thus, in Ca2+-free solution NH4Cl exposure led to a decrease in [Ca2+]i. This result and others suggest that, at constant pHe, intracellular alkalosis reduces [Ca2+]i, probably by enhancing sequestration of calcium. When cells were exposed to a CO2 transient at reduced pHe, Ca2+ rose initially but then fell, often below basal values. Similar results were obtained when extracellular HCO 3 - concentration was reduced at constant CO2 tension. Unexpectedly, such results were obtained only in Ca2+-containing solutions. In Ca2+-free solutions, acidosis always raised [Ca2+]i. It is suggested that a lowering of pHe stimulates extrusion of Ca2+ by ATP-driven Ca2+/2H+ antiport.

Key words

Calcium ions Neurons Acid-base changes Rat 

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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Y. B. OuYang
    • 1
  • P. Mellergård
    • 1
  • T. Kristián
    • 1
  • V. Kristiánova
    • 1
  • B. K. Siesjö
    • 1
  1. 1.Laboratory for Experimental Brain Research, Experimental Research CentreLund University HospitalLundSweden

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