Abstract
The effect of a dihydropyridine Ca 2+ antagonist, cilnidipine, on voltage-dependent Ca 2+ channels was studied in acutely dissociated rat CA1 pyramidal neurons using the nystatin-perforated patch recording configuration under voltage-clamp conditions. Cilnidipine had no effect on low-voltage-activated (LVA) Ca 2+ channels at the low concentrations under 10 −6 M. On the other hand, cilnidipine inhibited the high-voltage-activated (HVA) Ca 2+ current ( I Ca) in a concentration-dependent manner and the inhibition curve showed a step-wise pattern; cilnidipine selectively reduced only L-type HVA I Ca at the low concentrations under 10 −7 and 10 −6 M cilnidipine blocked not only L- but also N-type HVA I Ca. At the high concentration over 10 −6 M cilnidipine non-selectively blocked the T-type LVA and P/Q- and R-type HVA Ca 2+ channels. This is the first report that cilnidipine at lower concentration of 10 −6 M blocks both L- and N-type HVA I Ca in the hippocampal neurons.
Published Version
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