Spontaneous quantal and non-quantal release of acetylcholine at mouse endplate during onset of hypoxia.
At 20 (0)C, both quantal and non-quantal spontaneous acetylcholine release (expressed as miniature endplate potential frequency [f-MEPPs] and the H-effect, respectively) increased during the first 30 min of hypoxia in solution with normal extracellular calcium ([Ca(2+)](o) = 2.0 mM). The hypoxia-induced tenfold increase of the f-MEPPs was virtually absent in low calcium solution([Ca(2+)](o) = 0.4 mM) whereas there was still a significant increment of non-quantal release. This indicates that each of these two processes of acetylcholine release is influenced by mechanisms with different oxygen sensitivity. The rise of f-MEPPs during the onset of hypoxia apparently requires Ca(2+) entry into the nerve terminal, whereas the non-quantal release can be increased by another factors such as a lower level of ATP.
Bukharaeva
E A
EA
Institute of Biochemistry and Biophysics, Russian Academy of Sciences, Kazan State Medical University, Kazan Russia.
Salakhutdinov
R I
RI
Vyskocil
F
F
Nikolsky
E E
EE
D000109:Acetylcholine / Q000378:metabolism*; D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D009045:Motor Endplate / Q000378:metabolism / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology*
D000109:Acetylcholine