Intracellular calcium mobilization on stimulation of the muscarinic cholinergic receptor in chick limb bud cells

Abstract

Cell suspensions of chick limb buds (stage 23/24) were loaded with the fluorescent Ca chelator chlorotetracycline. Fluorescence was monitored in a spectrofluorometer. Stimulation with acetylcholine induced a fluorescence decrease, indicating intracellular Ca mobilization. The fluorescence decrease triggered by acetylcholine was inhibited by muscarinic but not by nicotinic antagonists, indicating that a muscarinic acetylcholine receptor is involved. The muscarinic receptor in the chick limb bud has a characteristic pharmacological profile: acetylcholine, carbachol and acetyl-β-methylcholine functioned as full agonists triggering maximal fluorescence decrease. Bethanechol was less effective, producing only one-third of the maximum response. Pilocarpine and oxotremorine, two classical agonists in other systems, were ineffective and functioned as antagonists. In the chick limb bud, cholinesterase, choline acetyltransferase and the presence of a muscarinic receptor have been demonstrated in previous studies. The present experiments show that stimulation of the embryonic muscarinic receptor leads to intracellular Ca mobilization.

Quantitative effects of some muscarinic agonists on evoked surface‐negative field potentials recorded from the guinea‐pig olfactory cortex slice

“…The poor efficacy of pilocarpine and bethanechol may reflect a partial agonist action as seen in sympathetic ganglia (Burgen & Spero, 1968;Brown et al, 1980), parasympathetic postganglionic neurones (Goyal & Rattan, 1978), embryonic chick limb bud cells (Schmidt et al, 1984), the phosphoinositide response in the brain (Fisher et al, 1983) and the inhibition of stimulated cyclic AMP formation in neuroblastoma cells (McKinney et al, 1985). These agonists are generally considered to show little or no activity at nicotinic receptors in ganglia (Caulfield & Stubley, 1982;Gilman et al, 1985) or skeletal muscle (Clague et al, 1985).…”

Insect cell lines as tools for studying ecdysteroid action

“…After cell differentiation, this muscarinic system disappears. In chicken limb buds it was shown that stimulation of the muscarinic receptor causes alterations in cell shape and movement (Schmidt et al, 1984;Oettling et al, 1985). Since a rise in acetylcholinesterase activity is also described for differentiation of non-nerve cells in Tenebrio molitor (Lenoir-Rousseaux and Gautron, 1987) and in developing imaginal discs of D. melanogarter (Spindler-Barth and Milner, unpublished), this "cholinergic system" may also play a role in insect cell differentiation.…”

Contraction wave in the chick blastoderm induced by muscarinic stimulation

“…The cholinesterase activity in non-neural cells indicated the involvement of a primitive cholinergic system, the components of which could be demonstrated biochemically in the embryo: cholinesterase activity was accompanied by expression of choline acetyltransferase (Reich and Drews 1983) and muscarinic receptors (Schmidt 1981). In cell suspensions, stimulation of the muscarinic receptor led to intracellular calcium mobilization (Schmidt et al 1984), which in turn could be used for the pharmacological characterization of the receptor itself (Oettling et al 1985).…”