Abstract
Despite the amount of work that has been done since Herter 1 first studied convulsant properties of indole, several points seemed worth clarifying. To this end, experiments were undertaken with the surgical assistance of Dr. Edward Davis.
In the first place, indole directly applied to the cortex of dog or cat produces a-localized discharge resembling in many ways that seen following local strychninization. This is apparent from Fig. 1. As with strychnine, the concentration required for local application to elicit these results is great.
On the other hand, rapid intravenous injections of 20 mg per kg into dogs, cats and rabbits bring on convulsions which differ from fits induced by cortical excitation in that the motions of various muscles are not synchronized, and in that the axial and axio-appendicular, not the appendicular, muscles are most involved. Yanai 2 has reported that seizures occur after decerebration, to which we can add that they are not significantly altered by decerebration.
After transection of the spinal cord, the seizures may be more pronounced and begin at lower concentrations of indole either below or above the transection. Frequently, following transection of the neuraxis at any level, both portions are involved independently. Fig. 2 exemplifies this in the decerebrate preparation. The top record is from the cortex, and the bottom is from the hind limbs. They show cortical electrical discharges unrelated to the twitches of the hind limbs.
Under full ether anaesthesia, several dogs and cats were prepared by inserting electrodes to follow the electrical activity and the oxygen tension of the cortex and by installing tracheal and arterial cannulae. Several hours were allowed for recovery from ether. They were then paralyzed with dihydro-β-erythroidine hydrobromide and given artificial respiration.
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