Turnover rate of the cardiac Na(+)-Ca2+ exchanger in guinea-pig ventricular myocytes.
AUTOR(ES)
Powell, T
RESUMO
1. Single guinea-pig ventricular myocytes were voltage clamped using the whole-cell configuration of the patch-clamp technique and membrane current generated by the Na(+)-Ca2+ exchange mechanism recorded. 2. Rapid increases in cytosolic free calcium ([Ca2+]i) evoked by flash photolysis of either nitr-5 or DM-nitrophen resulted in current relaxations, arising from a redistribution of exchanger carrier conformations induced by the changes in [Ca2+]i. 3. Relaxation time constants were temperature dependent with a temperature coefficient over a 10 degrees C range (Q10) of approximately 3 and also voltage dependent, decreasing on hyperpolarization for membrane potentials in the range +40 to -80 mV. 4. The experimental results are consistent with consecutive exchange models having electrogenic Na+ translocation steps, together with a site density and turnover rate similar to that for the Na(+)-K+ pump.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1160475Documentos Relacionados
- The role of the Na(+)-Ca2+ exchanger in the rate-dependent increase in contraction in guinea-pig ventricular myocytes.
- Inactivation of outward Na(+)-Ca2+ exchange current in guinea-pig ventricular myocytes.
- Ca2+ entry through Na(+)-Ca2+ exchange can trigger Ca2+ release from Ca2+ stores in Na(+)-loaded guinea-pig coronary myocytes.
- Isoprenaline, Ca2+ and the Na(+)-K+ pump in guinea-pig ventricular myocytes.
- Species differences in the activity of the Na(+)-Ca2+ exchanger in mammalian cardiac myocytes.