L-type calcium channels unmasked by cell-permeant Ca2+ buffer at mouse motor nerve terminals

The involvement of the different types of voltage-dependent calcium channels (VDCC) in both DM-BAPTA-AM-incubated and EGTA-AM-incubated mature mice levator auris neuromuscular junctions (NMJ) was studied. We evaluated the effects of ω-agatoxin IVA (ω-Aga IVA), nitrendipine and ω-conotoxin GVIA (ω-Cg...

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Detalles Bibliográficos
Autores principales: Urbano, F.J., Uchitel, O.D.
Formato: JOUR
Materias:
Calcium channel
Cell-permeant calcium buffers
DM-BAPTA-AM
EGTA-AM
Neuromuscular junction
calcium
calcium channel
calcium channel blocking agent
animal cell
animal experiment
animal tissue
article
calcium current
calcium transport
electrophysiology
male
mouse
nerve ending
nerve potential
neuromuscular synapse
neurotransmission
neurotransmitter release
nonhuman
priority journal
Animals
Buffers
Calcium
Calcium Channel Blockers
Calcium Channels
Calcium Channels, L-Type
Chelating Agents
Egtazic Acid
Electric Conductivity
Evoked Potentials
Male
Mice
Motor Endplate
Nitrendipine
omega-Agatoxin IVA
omega-Conotoxin GVIA
Peptides
Spider Venoms
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00316768_v437_n4_p523_Urbano
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:The involvement of the different types of voltage-dependent calcium channels (VDCC) in both DM-BAPTA-AM-incubated and EGTA-AM-incubated mature mice levator auris neuromuscular junctions (NMJ) was studied. We evaluated the effects of ω-agatoxin IVA (ω-Aga IVA), nitrendipine and ω-conotoxin GVIA (ω-CgTX) (P/Q-, L- and N-type VDCC blockers, respectively) on perineurial calcium currents (ICa) and nerve-evoked transmitter release. The application of ω-Aga IVA (100 nM) drastically reduced perineurial ICa (> 90%) and nerve-evoked transmitter release (> 90% of reduction in quantal content, m) at both DM-BAPTA-AM-incubated and EGTA-AM-incubated NMJ. The L-type VDCC antagonist nitrendipine (10 μM) caused a significant reduction (23 ± 9%, n = 5) of perineurial ICa at DM-BAPTA-AM-incubated NMJ. In addition, after the block of P/Q-type VDCC with ω-Aga IVA (100 nM), nitrendipine reduced (> 90%, n = 2) the remaining perineurial ICa. Such reduction was not observed at EGTA-AM-incubated NMJ, before or after the total block of P/Q-type VDCC. Moreover, nitrendipine did not significantly reduce the quantal content of DM-BAPTA-AM-incubated NMJ. Finally, the application of ω-CgTX (5 μM) did not significantly affect perineurial ICa or nerve-evoked transmitter release at either DM-BAPTA-AM-incubated or EGTA-AM-incubated NMJ. These results show the existence of a nitrendipine-sensitive, L-type component of perineurial ICa in DM-BAPTA-AM-incubated NMJ of mature mice. © Springer-Verlag 1999.

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