A re-evaluation of acetylcholine receptors on feline Renshaw cells

1 The effects of atropine, methylatropine and lachesine administered by ionophoresis were examined on responses of Renshaw cells to acetylcholine, acetyl-beta-methylcholine, nicotine and DL-muscarine in cats anaesthetized with pentobarbitone or chloralose. 2 The antagonists were as effective in antagonizing excitation by nicotine as they were in antagonizing excitation by acetylcholine and were only slightly more effective in antagonizing excitation by acetyl-beta-methylcholine. 3 These results are discussed in relation to the characterization of acetylcholine receptors on Renshaw cells. 4 It is concluded that there are two distinct populations of receptors but that the nicotinic receptors are non-selective in their activation by agonists and antagonists, whereas the muscarinic receptors display greater selectivity.