NICOTINOLYTIC DRUGS. II. ACTION OF ADRENERGIC BLOCKING AGENTS ON NICOTINE-INDUCED TREMORS

¹ Maltbie Laboratories, Morristown, N. J.

1. Nicotine-induced tremors in unanesthetized rabbits are unequivocally blocked by adrenergic blocking agents (Dibenamine, 933F and 883F). A linear relationship exists between the probit of rabbits protected and the logarithm of the dose of adrenergic blocking agent. The average effective dose is: Dibenamine 0.43 mgm./kgm., 883F 1.3 mgm./kgm. and 933F 2.4 mgm./kgm.

2. Tremors similar to nicotine are induced by other ganglionic stimulants: DMPP, 500 microgm.; acetylcholine, 15 microgm., after atropinizatien and eserinization.

3. Tremors induced by DMPP and acetylcholine are blocked by adrenergic blocking agents such as Dibenamine, 883F and 933F.

4. In the course of the experiments ether was found to potentiate the epinephrine pressor response in the rabbit.

5. There is no correlation between the production of tremors and the pressor response to nicotine.

6. Nicotine blocking agents are not necessarily adrenergic blocking agents. Adrenergic blockade does not necessarily relate to the prevention of nicotine tremors.

7. The blockade of nicotine-induced tremors by Dibenamine, 883F and 933F seems to be related in part to the blockade of endogenous epinephrine. The central nervous sytem and the motor end-plate of the skeletal muscle cannot be, however, excluded as the locus of blockade.