Inactivation of IA channels of frog skeletal muscle is modulated by ATP

Abstract:

Whole cell, voltage clamp experiments were performed in vesicles derived from frog skeletal muscle plasma membranes to characterize the influence of ATP on the kinetic properties of fast inactivating K⁺ currents (I<inf>A</inf>). IA was recorded in ATP-free solutions. Peak I<inf>A</inf> decayed with a time constant of 27 ms at large depolarizations. Steady state inactivation reached half maximal values at -66 mV. In the presence of ATP, these values were 196 ms and -41 mV, respectively, indicating a major effect of ATP on inactivation. In contrast, activation of I<inf>A</inf> was unaffected by ATP. The protein kinase C (PKC) inhibitors, H7 and staurosporine, greatly prevented the effects of ATP on inactivation. Inactivation remained unchanged by the protein kinase A inhibitor HA1004 or by the catalytic subunit of cAMP protein kinase. We conclude that ATP decreases inactivation of skeletal muscle I<inf>A</inf> and that this effect may be mediated by protein kinase C. © 2002 Elsevier Science (USA).

Año de publicación:

2002

Keywords:

• ATP
• inactivation
• Protein kinase C
• I currents A
• Skeletal muscle
• IA currents
• K channels

Fuente:

scopus