Actions of acetylcholine and carbachol on the chick biventer cervicis muscle

Abstract

Summary1. The possibility that carbachol may act on the chick biventer cervicis muscle by releasing acetylcholine was investigated. 2. Log dose-response curves for acetylcholine and carbachol were constructed in the presence of triethylcholine, tubocurarine and physostigmine, in both innervated and denervated chick biventer cervicis muscles. 3. The log dose-response curve for acetylcholine -was shallower than that for carbachol and was moved to the left by triethylcholine, indicating potentiation.In the presence of physostigmine, the curve was as steep as that for carbachol, and like that for carbachol was moved to the right by triethylcholine, indicating antagonism. In the presence of tubocurarine, the log dose-response curves for both acetylcholine and carbachol were moved to the right. 4. The log dose-response curves for both acetylcholine and carbachol were moved to the left by chronic denervation, indicating increased sensitivity to these drugs. Both curves were moved similar distances to the right by excess magnesium ion concentration. No tachyphylaxis developed to repeated administration of carbachol in the presence of triethylcholine or tubocurarine, either in innervated or denervated muscles. 5. It was concluded that the main action of triethylcholine in the chick biventer cervicis muscle is a tubocurarine-like action, which, in the presence of acetylcholine, is masked by a weak anticholinesterase action. It was also concluded that the diminished response to carbachol in the presence of triethylcholine is due to the postjunctional blocking action of triethylcholine. and that carbachol owes none of its activity to an ability to release acetylcholine from the nerve terminals.

Some Effects of the Aminoglycoside Antibiotic Amikacin on Neuromuscular and Autonomic Transmission

“…Thus, at ganglia, antibioticinduced depression of transmitter release would affect both responses to nerve stimulation and to added agonists. However, this cannot account for the observed depression of the responses to added agonists in the chick biventer cervicis muscle preparation as it has been shown that agonists act postjunctionally in this preparation (Marshall, 1971;Gandiha and Marshall, 1973).…”

Effects of quazodine (MJ 1988) on contractions of the isolated hemidiaphragm of the rat and the biventer cervicis muscle of the chick

“…progressively higher doses of quazodine enhanced responses to carbachol to a greater extent than responses to acetylchollne. This apparently greater potentiation of carbachol may be explained by the observation that in the chick biventer cervicis preparation the dose-response curve for carbachol is steeper than that for acetylcholine (Marshall, 1971). In fact when full dose-response lines were plotted from the results of seven further experiments, quazodine (200 ug/ml) caused parallel shifts of the log dose-response lines for acetylcholine and for carbachol corresponding to potentiation by 134 +0-12 and 1-41 + 0X08 fold respectively, and these factors are not significantly different.…”

Appearance of new acetylcholine receptors on the baby chick biventer cervicis and denervated rat diaphragm muscles after blockade with α‐bungarotoxin

“…in this muscle attains about 90% of that obtained by tetanic stimulation. Denervation of the chick biventer cervicis muscle was performed as described by Marshall (1971) under ether anaesthesia.…”