Effects of T-type, L-type, N-type, P-type, and Q-type calcium channel blockers on stimulus-induced pre-and postsynaptic calcium fluxes in rat hippocampal slices

摘要: The contribution of T-, L-, N-, P-, and Q-type Ca2+ channels to pre-and postsynaptic entry during stimulus-induced high neuronal activity in area CA1 rat hippocampal slices was investigated by measuring the effect specific blockers on decreases extracellular concentration ([Ca2+]0). [Ca2+]0 measured with ion-selective electrodes stratum radiatum (SR) pyramidale (SP), while into neurons induced stimulus trains (20 Hz for 10 s) alternately delivered SR alveus, respectively. recorded response stimulation represented mainly presynaptic (Capre), SP alvear were predominantly based (Capost). Ethosuximide trimethadione ineffective m concentrations up 1 mM. At mM, they reduced Capost and, much less, also Capre Nimodipine (25 μM) a minor extent, Capre. ω-Agatoxin IVA (0.4–1 ω-conotoxin MVIIC (1 both Capost, but stronger action ω-Conotoxin GVIA (3–8 without We conclude that stimulus-induced, high-frequency is carried P/Q-, L-type probably further channel type different from these channels. includes at least P/Q-and possibly N-type did not contribute our experiments. Since ethosuximide only effective concentrations, their may be unspecific. Thus, T-type do seem play major part this situation.