THE RELATIONSHIP BETWEEN CHOLINESTERASE INHIBITION AND GANGLIONIC TRANSMISSION

¹ Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York City

1. The mode of action of DFP at a sympathetic ganglionic site was investigated by recording contractions of the nictitating membrane during preganglionic stimulation in atropinized cats and determining the degrees of inactivation of ganglionic specific and non-specific ChE's.

2. The dose of DFP (0.25 mgm. per kgm. i.v.) which produced complete inactivation of non-specific ChE and 44 per cent inactivation of specific ChE caused no potentiation of the height of contraction or antagonism of intra-arterially injected TEA. At dose levels of 0.5 to 2.0 mgm. per kgm., where specific ChE was progressively inactivated, there was a concomitant increase in the potentiation of contraction and antagonism of TEA. At higher dosage levels, decreased height of contraction and diminished TEA antagonism were usually observed.

3. It is concluded that the action of DFP on the superior cervical ganglion is dependent primarily upon the inhibition of specific ChE.