III. The Action of Atropine in Counteracting the Effects of Pituitrin and of Pilocarpine Injected into the Cerebral Ventricles

In the two preceding papers it has been shown: (1) that the intraventricular injection of pituitrin leads to a striking response characterized by nausea and vomiting, flushing, sweating, salivation and a marked fall in body temperature usually though not always accompanied by a drop in the basal metabolic rate; and (2) that a reaction of surprisingly similar type promptly follows the intraventricular injection of pilocarpine. Since we have in atropine an effective antidote to pilocarpine, it was felt that should the reaction of pilocarpine by way of the ventricle be checked by atropine, we might expect the pituitrin reaction to be similarly checked if the two substances, the drug and the extract, in the production of their similar effects, actually operated through the same and probably central nervous mechanism. On one or two occasions when the reaction to pituitrin had been more marked than expected and the subject was rendered unduly uncomfortable from the recurrent retching and vomiting, it had been observed that an irtjection of 1 mgm. of atropine and 5 mgm. of morphia effectually checked the reaction. Under this suggestive lead, the matter was first put to test as follows: