title: Binding of alpha-bungarotoxin to chick sympathetic ganglia: properties of the receptor and its rate of appearance during developement.
abstract: Studies were carried out on the binding of [125I]alpha-bungarotoxin (alphaBT) to membrane fragments of chick sympathetic ganglia. Specific binding of toxin was saturable with a KD of 1.1 nM. The rates of association and dissociation of the toxin from ganglionic membranes were 4.3 X 10(4) M-1 sec-1 and 4.6 X 10(-5) sec-1 (t 1/2 = 4.2 h). respectively. Binding was inhibited (by up to 95%) by low concentrations of nicotinic, but not by a muscarinic cholinergic ligand. The properties of the ganglionic binding site for alphaBT were consistent with its being a nicotinic acetylcholine receptor. The development of toxin receptors in chick ganglia was also studied. From days 7 to 11 in ovo, few receptors were present; from days 12 to 20 in ovo, there was a 10-fold increase in receptor number per ganglion; from hatching to maturity, the receptor number per ganglion slowly increased and reached a maximum of 14 fmoles. The ontogeny of receptors for alphaBT in sympathetic ganglia appears to correlate with the cytological maturation and innervation of the principal neurons.
mesh_terms: D000367:Age Factors; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002038:Bungarotoxins / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002642:Chick Embryo; D002645:Chickens; D005703:Gallamine Triethiodide / Q000494:pharmacology; D005725:Ganglia, Autonomic / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D011955:Receptors, Drug; D014403:Tubocurarine / Q000494:pharmacology
chemical_list: D002038:Bungarotoxins; D011955:Receptors, Drug; D001285:Atropine; D002217:Carbachol; D005703:Gallamine Triethiodide; D014403:Tubocurarine