Effects of a few quaternary ammonium compounds on the cardio-vascular responses of acetyl choline in dog.

Decisive evidence for acetyl-choline as a chemical transmitter has accumulated during the last 20 years. Chemically acetyl.choline is a quaternary ammonium compound and it is but natural to expect that substances analogous to this chemical grouping would have actions of preserving, mimicking or antagonising the natural chemical transmitter at the receptors sensitive to it. This is found to be correct and as a consequence thereof, a host of quarternary ammonium compounds have been prepared and tested. These compounds have been found varied in their actions. Decamethonium, d·tubocurarine etc. resemble acetyl-choline very closely at the neuro muscular junctions. On the contrary, Tetraethyl ammonium chloride, Hexamethonium and others antagonise it specifically at the ganglionic synapses.