ISSN:
1432-1912
Keywords:
Intrinsic Acetylcholine Receptor
;
Extrinsic Acetylcholine Receptor
;
Anticholinesterase
;
α-Bungarotoxin
;
Chick Biventer Cervicis Muscle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The intrinsic and extrinsic acetylcholine receptors were studied by analysing the effects of α-bungarotoxin and desipramine on the contractile response elicited by nerve stimulation (single shocks) and that by application of acetylcholine. In the absence of anticholinesterases, α-bungarotoxin as well as desipramine blocked the response to exogenous acetylcholine with a time-course much faster than that of the inhibition of the response to nerve stimulation. After complete blockade of neuromuscular transmission by α-bungarotoxin, washout of the toxin gradually resulted in recovery of the response to acetylcholine, whereas the response to nerve stimulation was not appreciably restored. (+)-Tubocurarine, on the other hand, blocked both types of responses to a parallel extent. (+)-Tubocurarine as well as acetylcholine at high concentration protected both responses from blockade by α-bungarotoxin. In the presence of anticholinesterases, the inhibition by α-bungarotoxin of responses to nerve stimulation and to acetylcholine was parallel. The recovery of acetylcholine-induced responses after washout of the toxin, however, was smaller than in the absence of anticholinesterases. It is concluded that the extrinsic and intrinsic acetylcholine receptors belong to different populations and also have different properties. In the absence of anticholinesterases, exogenous acetylcholine acts upon the extrinsic receptors only, while in the presence of anticholinesterases, the intrinsic receptors are affected.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00500986
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