Modulation of high-voltage-activated calcium channels in rat CNS neurons

The pharmacological properties and developmental changes of the high-voltag e activated (HVA) Ca2+ channel currents were studied in neurons acutely dis sociated from various CNS regions of the rat with the nystatin perforated p atch recording configuration under voltage-clamp conditions. Five different types of HVA Ca2+ channels were distinguished pharmacologically; dihydropy ridine sensitive L-type, omega-conotoxin-GVIA sensitive N-type, omega-agato xin-IVA sensitive P-type, omega-conotoxin-MVIIC sensitive Q-type, and R-typ e which is insensitive to these organic Ca2+ antagonists. The five types of HVA Ca2+ channels differed considerably in their distribution among variou s CNS neurons and were developmentally regulated, reaching the adult level within 2 weeks after birth. In 2-week-old rat CNS neurons, the neurotransmi tters inhibited several types of HVA Ca2+ channels differently. Nilvadipine , a dihydropyridine derivative, selectively suppressed L-type Ca2+ channel. These results suggest that selective modulation of the developmentally reg ulated five types of HVA Ca2+ channels by neurotransmitters and synthesized Ca2+ antagonists may be a key determinant in regulating Ca2+ homeostasis i n various CNS neurons.