Effects of innervation by ciliary ganglia on developing muscle in vitro
article
Electrophysiological and pharmacological properties of neuromuscular junctions formed in tissue culture between chick ciliary ganglia and chick skeletal muscle cells have been studied. Functional neuromuscular junctions are formed already within 24h. No functional acetylcholine (ACh) esterase is present at these endplates. The neurites conduct action potentials to the neuromuscular junctions, where EPPs are generated. Tetrodotoxin (TTX) blocks this nerve conduction but in the presence of TTX MEPP-like potentials remain whose amplitudes are lowered when the Mg2+/Ca2+ ratio in the medium is raised. It is speculated that these large TTX-resistant potentials are multiquantal. The relatively high resting membrane potential in non innervated muscle fibers was not changed by innervation. ACh-sensitivity was determined by iontophoretical application of ACh to the myotubes. Non-innervated myotubes exhibited an evenly distributed ACh-sensitivity. Local differences in ACh-sensitivity were always gradual and never exceeded a factor of 3. Innervation did not alter the overall ACh-sensitivity, but on functionally innervated muscle cells loci hypersensitive to ACh were found. Hypersensitivity was located within sharply defined areas. Apparently the para-sympathetic neurons of the ciliary ganglion are able to form functional neuromuscular junctions with skeletal muscle cells in tissue culture and to induce the formation of regions of high ACh-sensitivity. Chemicals/CAS: acetylcholine, 51-84-3, 60-31-1, 66-23-9; acetylcholinesterase, 9000-81-1; tetrodotoxin, 4368-28-9, 4664-41-9; Atropine, 51-55-8; Physostigmine, 57-47-6; Tetrodotoxin, 4368-28-9; Tubocurarine, 57-95-4
Topics
AcetylcholineAcetylcholinesteraseTetrodotoxinAnimal experimentChickenCiliary ganglionEndplate potentialIn vitro studyMuscleNeuromuscular synapseTissue cultureAnimalAtropineCells, CulturedChick EmbryoElectric StimulationGanglia, ParasympatheticMembrane PotentialsMotor EndplateMusclesPhysostigmineTetrodotoxinTubocurarine
TNO Identifier
228640
ISSN
00068993
Source
Brain Research, 175(1), pp. 87-107.
Pages
87-107
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