Altered properties of quantal neurotransmitter release at endplates of mice lacking P/Q-type Ca2+ channels

• Autores: Urbano, F.J.; Piedras-Rentería, E.S.; Jun, K.; Shin, H.-S.; Uchitel, O.D.; Tsien, R.W.
• Año de publicación: 2003
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Proc. Natl. Acad. Sci. U. S. A. 2003;100(6):3491-3496
• Materia: α1A knockout; Ca2+-activated potassium channel; Neuromuscular junction; Paired-pulse facilitation; SNX-482; calcium channel; calcium ion; cholinergic receptor; magnesium ion; action potential; animal cell; article; channel gating; exocytosis; mouse; nerve ending; neuromuscular synapse; neurotransmission; neurotransmitter release; nonhuman; priority journal; 4-Aminopyridine; Animals; Calcium Channels, N-Type; Calcium Channels, P-Type; Calcium Channels, Q-Type; Calcium Channels, R-Type; Mice; Mice, Knockout; Models, Neurological; Motor Endplate; Neuronal Plasticity; Neurotransmitter Agents; Synaptic Transmission; Animalia
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

Transmission at the mouse neuromuscular junction normally relies on P/Q-type channels, but became jointly dependent on both N-and R-type Ca2+ channels when the P/Q-type channel α1A subunit was deleted. R-type channels lay close to Ca2+ sensors for exocytosis and IK(Ca) channel activation, like the P/Q-type channels they replaced. In contrast, N-type channels were less well localized, but abundant enough to influence secretion strongly, particularly when action potentials were prolonged. Our data suggested that active zone structures may select among multiple Ca2+ channels in the hierarchy P/Q>R>N. The α1A-/- neuromuscular junction displayed several other differences from wild-type: lowered quantal content but greater ability to withstand reductions in the Ca2+/Mg2+ ratio, and little or no paired-pulse facilitation, the latter findings possibly reflecting compensatory mechanisms at individual release sites. Changes in presynaptic function were also associated with a significant reduction in the size of postsynaptic acetylcholine receptor clusters.
Fil:Uchitel, O.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.