The number of muscarinic receptors in chick amnion muscle

Abstract

Summary [3H]‐Propyl benzilylcholine mustard ([3H]‐PrBCM) an irreversible specific antagonist of muscarinic acetylcholine receptors, has been used to label the muscarinic receptors in the aneuronal muscle of isolated 11 day amniotic membranes of chick embryos. This muscle was found to have about 9 fmol/mg dry weight of receptor material. This is only 1–2% of the amount found in intestinal muscle. Pharmacological studies with isolated amniotic membranes using PrBCM show that labelling is to functional receptors and that the receptor reserve is small. The significance of the difference in receptor reserve in innervated and aneuronal plain muscle is discussed.

THE BINDING OF [3H]‐PROPYLBENZILYLCHOLINE MUSTARD BY LONGITUDINAL MUSCLE STRIPS FROM GUINEA‐PIG SMALL INTESTINE

“…curves have been obtained with receptors in brain synaptosomes (Burgen,Hiley & Young, 300 C published observations) and chick amnion (Cuthbert & Young, 1973). The failure of the Recovery 2 x 10-6 (1) s-' 6.6 ± 2.0 x 10-6 (4) s-' kinetics of atropine uptake to satisfy a mass action of receptor equation for a simple receptor species (Paton & availability Rang, 1965) may represent another aspect of the Loss of 1 x 10-6 (2) s -6.2 ± 1.4 x 10-6 (3) s-l same problem.…”

Ligand Binding to Muscarinic Receptors in Intact Longitudinal Muscle Strips From Guinea‐pig Intestine

“…Some of these studies, like the original, have used pharmacologically intact tissues, generally in conjunction with the use of an irreversible ligand (Rang, 1967;Cuthbert & Young, 1973;Fewtrell & Rang, 1973;Burgen, Hiley & Young, 1974a), but there are a number of experimental difficulties in this approach and most groups have preferred to work with tissue homogenates where equilibrium measurements with reversible ligands can be conveniently made and where statistical errors are generally small. The values of the binding affinities for antagonists obtained by the use of tissue homogenates are in general in excellent agreement with those determined from inhibition of the contractile response .…”

Mechanisms for the effects of acetylcholine on sodium transport in frog skin

“…Muscarinic receptors in epithelia and intestinal muscle were measured using the irreversible ligand propylbenzilylcholine mustard with methods similar to those used by Cuthbert and Young (1973) for amniotic membranes. The label was cyclized in 10 mg phosphate buffer, at pH 7.6 for 1 hr.…”