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Acetylcholine regulation of nicotinic receptor channels through a putative G protein in chick myotubes.
Author(s) -
Eusebi F,
Grassi F,
Molinaro M,
Zani B M
Publication year - 1987
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1987.sp016845
Subject(s) - acetylcholine , patch clamp , guanosine , nicotinic agonist , acetylcholine receptor , g protein , nicotinic acetylcholine receptor , biophysics , second messenger system , gtp' , extracellular , chemistry , medicine , microbiology and biotechnology , biology , endocrinology , intracellular , biochemistry , receptor , enzyme
1. Single‐channel currents induced by acetylcholine (ACh) were recorded from unstriated and non‐innervated embryonic chick myotubes using the cell‐attached patch‐clamp technique. 2. ACh applied to the non‐patched membrane decreased both channel opening probability and conductance. These ACh‐induced effects occurred also when the non‐patched membrane was exposed to nominally Ca2+‐free extracellular medium, but were absent when it was treated with curare. 3. ACh‐induced membrane current recorded under whole‐cell patch‐clamp conditions decreased in amplitude and time course when myotubes were intracellularly loaded with guanosine‐5'‐O‐(3‐thiotriphosphate) GTP gamma S), but not with guanosine‐5'‐O‐(2‐thiodiphosphate) (GDP beta S) or cyclic adenosine‐5'‐monophosphate (cyclic AMP). Internal perfusion of GTP gamma S affected the ACh‐induced openings in a similar manner to the non‐patch ACh application. 4. These results suggest that ACh, in addition to its direct effect, acts indirectly on the nicotinic receptor channels by delivering an intracellular messenger and through the activation of a putative G protein.