Figure 1.

Membrane depolarization and Ca²⁺ channel window currents in hCa_v1.2b-transfected CHO cells. (A) Current clamp recording showing depolarization to a steady membrane potential of −6 mV by perfusion with 80 mM KCl-HEPES buffer. (B) Ca²⁺ channel window currents obtained by overlap of Boltzmann fits for voltage dependent inactivation and activation curves. Inset: Detail of the window current potential range. (C) Time dependent pCREB expression by 80 mM KCl. The hCa_v1.2b transfected CHO cells were treated with 80 mM KCl for 0 to 120 min and pCREB expression normalized to total CREB. (D) Inhibition of pCREB expression by nifedipine (1 µM) and peroxynitrite (150 µM). CHO cells were incubated with either nifedipine (NIF) or peroxynitrite (ONOO^-) for 30 min prior to depolarization for 30 min by KCl. Ratio of phospho-CREB to total CREB are presented in the bottom panels as mean ± SD (n= 3). *P < 0.001 versus KCl. CREB, cyclic AMP response element binding protein.