Comparison between slow sodium channel inactivation in rat slow- and fast-twitch muscle.

AUTOR(ES)

Ruff, R L

RESUMO

1. Voltage-clamp Na+ currents (INa) were studied in rat soleus slow-twitch muscle fibres at about 18 degrees C using the loose-patch-clamp technique. The maximum inward current density was produced by depolarizations to about -19 mV. 2. Fast inactivation was studied utilizing 20 ms conditioning potentials. INa was reduced by 50% with conditioning potentials to about -70 mV. 3. Changes in the conditioning membrane potential produced slow changes in the peak INa due to a slow inactivation process. INa was reduced by 50% at about -86 mV due to slow inactivation. 4. The mean maximum inward INa when slow inactivation was fully removed was 6.83 mA cm-2. 5. Due to the slow inactivation process, slow-twitch fibres were less susceptible to reduction in INa than fast-twitch fibres.

Documentos Relacionados

• Slow sodium channel inactivation in rat fast-twitch muscle.
• Action potential generation in rat slow- and fast-twitch muscles.
• Calcium action potentials in rat fast-twitch and slow-twitch muscle fibres.
• Asymmetrical charge movement in slow- and fast-twitch mammalian muscle fibres in normal and paraplegic rats.
• Force-dependent and force-independent heat production in single slow- and fast-twitch muscle fibres from Xenopus laevis.