Cytosolic free magnesium concentration in cultured chick heart cells.
Am J Physiol
; 257(1 Pt 1): C141-6, 1989 Jul.
Article
em En
| MEDLINE
| ID: mdl-2750886
ABSTRACT
Cytosolic free magnesium (Mgi) was measured in embryonic chick heart cells loaded with one of two newly developed 19F nuclear magnetic reasonance (NMR)-sensitive magnesium chelators, 4-methyl,5-fluoro-2-aminophenol-N,N,O-triacetate (MF-APTRA) and 5-fluoro-2-aminophenol-N,N,O-triacetate (5F-APTRA). The cells, embedded in strands of collagen, were superfused at a rate that allowed for solution changes in 2 min. In this preparation 19F- and 31P-NMR spectra were stable for at least 3.5 h. Because Na-coupled Mg countertransport may be a possible mechanism of Mg transport, in some experiments extracellular Na was reduced to 1 mM (choline substituted). This manipulation caused a 2.5-fold increase in Mgi from the basal level of 0.56 mM. A significant proportion of this increase in Mgi could be secondary to an increase in Cai that occurs with low extracellular Na (Nao) perfusion (Nai-Cao exchange). Perfusing cells with nominally Ca-free, 1 mM Na salt solution substantially attenuated the increase in Mgi that occurred with Ca present (1.25 mM) in the low Na (1 mM) solution. Furthermore, perfusion with 1 mM Na, Mg-free salt solution caused a 1.5-fold increase in Mgi, which cannot be attributable to Nai-Mgo exchange. Therefore attempts to describe the regulation of Mgi in heart cells must differentiate between the effects of Nai-Mgo exchange and competition for binding sites that are secondary to stimulation of ion gradient-coupled mechanisms.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Citosol
/
Magnésio
/
Miocárdio
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1989
Tipo de documento:
Article