Role of Na+/Ca2+ exchange in [Ca2+]i clearance in rat culture Purkinje neurons requires reevaluation.
Jpn J Physiol
; 53(4): 259-69, 2003 Aug.
Article
em En
| MEDLINE
| ID: mdl-14606965
Previous studies have shown that in contrast to other neuronal cells, Na(+)/Ca(2+) exchange contributes little to Ca(i)(2+) homeostasis in rat cerebellar Purkinje neurons under intracellular perfused conditions and at room temperature [Fierro et al.: J Physiol (Lond) 510: 499-512, 1998]. The purpose of this study was to clarify the role of this transporter in cerebellar Purkinje neurons by using intact cells at nearly physiological body temperature. Using Fluo-3 microfluorometry, we have examined the role of the Na(+)/Ca(2+) exchange in the buffering of calcium loads in cultured rat Purkinje neurons at two temperatures: 20 and 34 degrees C. At 20 degrees C, the recovery of the K(+)-induced [Ca(2+)](i) signal was little affected by the presence of external Na(+) (tau(e) = 35.5 +/- 1.2 s [n = 49]), or by its absence (tau(e) = 36.6 +/- 2.2 s [n = 29]), i.e. in a Li(+)-containing medium. In contrast, at 34 degrees C, the recovery of the [Ca(2+)](i) signal was highly dependent on external Na, i.e. tau(e) = 19.9 +/- 1.2 s (n = 119) and tau(e) = 41.7 +/- 2.6 s (n = 39), in Li(+)-containing media, respectively. A comparison of the rate of clearance of [Ca(2+)](i) in Na(+) or Li(+) media, shows that at a room temperature of 20 degrees C, the Na(+)/Ca(2+) exchange contributes at most to 15-20% of the total [Ca(2+)](i) clearance, compared to 55-65% at 34-36 degrees C. We also demonstrate that under normal physiological conditions forward and reverse Na(+)/Ca(2+) exchanges operate in the same neuron. We conclude that the Na(+)/Ca(2+) exchange is strongly suppressed at room temperature and therefore its role should be reevaluated among different neuronal preparations.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Células de Purkinje
/
Cálcio
/
Trocador de Sódio e Cálcio
Limite:
Animals
Idioma:
En
Revista:
Jpn J Physiol
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Venezuela
País de publicação:
Japão