Recepción del artículo: 16 de Noviembre, 2004

Aprobación: 17 de Enero, 2005

Primera edición: 17 de Mayo, 2005

Palabras clave

Clasificación en siicsalud
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Especialidades
Principal: Bioquímica
Relacionadas: Medicina Interna

Patrocinio y reconocimiento
Agradecimientos: Apoyado por la Agencia Nacional de Promoción Científica y Tecnológica (FONCYT PICT03/ 05-12397) y la Agencia Córdoba Ciencia (181/01). G. B. es miembro de la Carrera del Investigador del Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET). S. G. R. es investigador asociado al laboratorio de Biofísica del IMMF.

METABOLIC REGULATION OF BRAIN Na⁺/Ca²⁺ EXCHANGE

Abstract
The Na⁺/Ca²⁺ exchanger couples movement of Na⁺ and Ca²⁺ across the plasma membrane of most animal cells. Several intra- and extra-cellular ligands ( Ca²⁺, H⁺, Na⁺, K⁺, ATP, phosphoarginine, phospholipids) modulate the function of this exchanger. Mg-ATP activates the Na⁺/Ca²⁺ exchanger in membrane vesicles from bovine heart (K_0.5, 500 μM) and brain (K_0.5, 336 μM). As a difference with the squid nerve this effect has no need of any cytosolic component. Also, stimulation is the same in bovine brain vesicles prepared and/or assayed at mammals (160 mM) or marine animals (300 mM) ionic strength. Other differences between squid and bovine brain are: (i) bovine brain Na⁺/Ca²⁺ exchanger is not stimulated by phosphagens, either phosphoarginine or phosphocreatine and (ii) in bovine brain stimulation by MgATP is related to the production of poly-phosphatidylinositides. In this regard bovine heart and brain Na⁺/Ca²⁺ exchangers behave similarly. Cardiac Na⁺/Ca²⁺ exchanger binds PtdIns-4,5-P2 and MgATP regulates that binding in the same direction of Na⁺/Ca²⁺ fluxes. These results indicate that metabolic regulation of the squid and mammalian nerve Na⁺/Ca²⁺exchangers are not alike and represent differences between species.

Key words
Na⁺/Ca²⁺ exchange, ATP, bovine brain, phosphoinositides, phosphagens

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