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Titolo:
Role of mitochondrial dysfunction in the Ca2+-induced decline of transmitter release at K+-depolarized motor neuron terminals
Autore:
Calupca, MA; Hendricks, GM; Hardwick, JC; Parsons, RL;
Indirizzi:
Univ Vermont, Coll Med, Dept Anat & Neurobiol, Burlington, VT 05405 USA Univ Vermont Burlington VT USA 05405 Neurobiol, Burlington, VT 05405 USA Ithaca Coll, Dept Biol, Ithaca, NY 14850 USA Ithaca Coll Ithaca NY USA 14850 aca Coll, Dept Biol, Ithaca, NY 14850 USA
Titolo Testata:
JOURNAL OF NEUROPHYSIOLOGY
fascicolo: 2, volume: 81, anno: 1999,
pagine: 498 - 506
SICI:
0022-3077(199902)81:2<498:ROMDIT>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
PERMEABILITY TRANSITION PORE; TRANSVERSUS ABDOMINIS MUSCLE; FROG NEUROMUSCULAR-JUNCTION; ADRENAL CHROMAFFIN CELLS; CEREBELLAR GRANULE CELLS; SNAKE TWITCH; GARTER SNAKE; CALCIUM LOADS; CA2+ LOADS; ENDOCYTOSIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: Parsons, RL Univ Vermont, Coll Med, Dept Neurobiol & Anat, Burlington, VT 05401 USA Univ Vermont Burlington VT USA 05401 Burlington, VT 05401 USA
Citazione:
M.A. Calupca et al., "Role of mitochondrial dysfunction in the Ca2+-induced decline of transmitter release at K+-depolarized motor neuron terminals", J NEUROPHYS, 81(2), 1999, pp. 498-506

Abstract

The present study tested whether a Ca2+-induced disruption of mitochondrial function was responsible for the decline in miniature endplate current (MEPC) frequency that occurs with nerve-muscle preparations maintained in a 35 mM potassium propionate (35 mM KP) solution containing elevated calcium. When the 35 mM KP contained control Ca2+ (1 mM), the MEPC frequency increased and remained elevated for many hours, and the mitochondria within twitchmotor neuron terminals were similar in appearance to those in unstimulatedterminals. All nerve terminals accumulated FM1-43 when the dye was presentfor the final 6 min of a 300-min exposure to 35 mM KP with control Ca2+. In contrast, when Ca2+ was increased to 3.6 mM in the 35 mM KP solution, theMEPC frequency initially reached frequencies >350 s(-1) but then graduallyfell approaching frequencies <50 s(-1). A progressive swelling and eventual distortion of mitochondria within the twitch motor neuron terminals occurred during prolonged exposure to 35 mM KP with elevated Ca2+. After similarto 300 min in 35 mM KP with elevated Ca2+, only 58% of the twitch terminals accumulated FM1-43. The decline in MEPC frequency in 35 mM KP with elevated Ca2+ was less when 15 mM glucose was present or when preparations were pretreated with 10 mu M oligomycin and then bathed in the 35 mM KP with glucose. When glucose was present, with or without oligomycin pretreatment, a greater percentage of twitch terminals accumulated FM1-43. However, the mitochondria in these preparations were still greatly swollen and distorted. Wepropose that prolonged depolarization of twitch motor neuron terminals by 35 mM KP with elevated Ca2+ produced a Ca2+-induced decrease in mitochondrial ATP production. Under these conditions, the cytosolic ATP/ADP ratio was decreased thereby compromising both transmitter release and refilling of recycled synaptic vesicles. The addition of glucose stimulated glycolysis which contributed to the maintenance of required ATP levels.

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Documento generato il 05/12/20 alle ore 19:24:15