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Pflügers Archiv

, Volume 444, Issue 5, pp 677–684 | Cite as

MgATP and phosphoinositides activate Na+/Ca2+ exchange in bovine brain vesicles. Comparison with other Na+/Ca2+ exchangers

  • Graciela Berberián
  • Carla Asteggiano
  • Cuong Pham
  • Shirley Roberts
  • Luis Beaugé
Original Article

Abstract.

We investigated the metabolic modulation of the Na+/Ca2+ exchanger in membrane vesicles obtained from bovine brain. The Na+/Ca2+ exchanger was activated by MgATP with a K 0.5 of 336 µM. Unlike the squid nerve Na+/Ca2+ exchanger, this effect required no cytosolic component. Also, stimulation is the same in vesicles prepared and/or assayed at the ionic strength found in mammals (160 mM) or marine animals (300 mM). Other differences between squid and bovine nerve are that the bovine brain Na+/Ca2+ exchanger is not stimulated by phosphagens, either phosphoarginine (molluscan source) or phosphocreatine (mammalian source); and that stimulation by MgATP in bovine brain is related to the production of polyphosphatidylinositides. In this regard bovine heart and brain Na+/Ca2+ exchangers behave similarly. These results indicate that the mechanisms of metabolic regulation of the squid and mammalian nerve Na+/Ca2+ exchangers are not alike and represent differences between species. Some differences found between bovine heart and brain exchangers, such as MgATP stimulation even at saturating [Ca2+] and the smaller degree of activation by adenosine 5′-O-(3-thiotriphosphate) (ATP-γ-S) in the brain, may be related to the unequal isoform population in both tissues.

Na+/Ca2+ exchange ATP Bovine brain Phosphoinositides Phosphagens 

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Graciela Berberián
    • 1
  • Carla Asteggiano
    • 1
  • Cuong Pham
    • 1
  • Shirley Roberts
    • 1
  • Luis Beaugé
    • 1
  1. 1.Laboratorio de Biofísica, Instituto de Investigación Médica Mercedes y Martín Ferreyra, Casilla de Correo 389, 5000 Córdoba, Argentina

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