Structure-linked latency of muscarinic receptors in axonal transport.
Muscarinic receptors that accumulated above a ligature in rat sciatic nerves were labelled in vitro under isotonic conditions with N-[3H]methylscopolamine. The addition of 0.005% of digitonin doubled the binding in proximal segments above and close to the ligature but not in the intermediary segments between two ligatures. Osmotic shock and freeze-thawing treatments also enhanced the binding. Digitonin did not affect the affinity of muscarinic receptors but revealed a greater number of sites by increasing the membrane permeability to the hydrophilic ligand. We conclude that presynaptic muscarinic receptors that undergo fast axonal transport in rat sciatic nerves exist under a latent form because they are associated with vesicles. This is the first demonstration of a structure-linked latency for receptors.
D000818:Animals; D001370:Axonal Transport; D004072:Digitonin / Q000494:pharmacology; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D008297:Male; D019832:N-Methylscopolamine; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*; D012584:Sciatic Nerve / Q000378:metabolism*; D012602:Scopolamine Derivatives / Q000378:metabolism*
D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D004299:Dopamine beta-Hydroxylase; D004072:Digitonin; D019832:N-Methylscopolamine