Characterization of Na+-Ca2+ exchange activity in plasma membrane vesicles from postmortem human brain

Gary Hoel, Mary L. Michaelis, William J. Freed, J. E. Kleinman

Research output: Contribution to journalArticlepeer-review

Abstract

Procedures were developed for measurement of Na+/Ca2+ exchange in resealed plasma membrane vesicles from postmortem human brain. The vesicle preparation method permits use of stored frozen tissue with minimal processing required prior to freezing. Vesicles prepared in this manner transport Ca2+ in the presence of a Na+ gradient. The kinetic characteristics of the Na+/Ca2+ exchange process were determined in membrane vesicles isolated from hippocampus and cortex. The Kact for Ca2+ was estimated to be 32 μM for hippocampal and 17 μM for cortical tissue. The maximal rate of Ca2+ uptake (Vmax) was 3.5 nmol/mg protein/15 sec and 3.3 nmol/mg protein/15 sec for hippocampal and cortical tissue, respectively. Exchange activity was dependent on the Na+ gradient, and was optimal in the high pH range. Therefore, membranes in which Na+-dependent o Ca2+ transport activity is preserved can be isolated from postmortem human brain and could be used to determine the influence of pathological conditions on this transport system.

Original languageEnglish (US)
Pages (from-to)881-887
Number of pages7
JournalNeurochemical Research
Volume15
Issue number9
DOIs
StatePublished - Sep 1990
Externally publishedYes

Keywords

  • Ca transport
  • Na-Ca exchange
  • human brain
  • synaptic membranes

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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