The ganglion-stimulating effects of some amino-acid esters.

1. The effects of some amino-acid esters possessing both muscarinic and nicotinic activity have been investigated on the cat superior cervical ganglion. The compounds were applied to the ganglion in vivo by close intra-arterial injection and responses were measured by contraction of the nictitating membrane or by recording post ganglionic compound action potentials.2. The esters, like carbachol, produced effects which were blocked by hexamethonium and reduced by atropine. Pretreatment with an anticholinesterase agent had no effect on the response and the chronically denervated ganglion was, if anything, slightly more sensitive to the drugs.3. Effects of standard muscarinic and nicotinic drugs were also studied and the results support the view that both muscarinic and nicotinic receptors are present in the ganglion.4. From the results of this investigation it appears that the amino-acid esters and carbachol produce their effects by interacting with post synaptic receptors in the ganglion. This is in contrast to other results in the literature which suggest that the receptors might be presynaptic. Further studies are required to resolve this difference.