Abstract
As indicated by behavior and the electrical activity of the nervous and muscular systems of the salamander, pentylenetetrazol and picrotoxin induce seizures with tonic and clonic phases. These drugs evoke a clonic-tonic type of seizure in the absence of a cerebral cortex. After a transection of the spinal cord neither drug evokes spastic jerks posterior to the transection. Hence lower centers of the brain are required for the combined manifestation of clonic and tonic seizures induced by these two drugs.
Strychnine lowers the threshold to stimulation, and after transection evokes generalized spastic twitches on either side of the cut, suggesting an action of the drug on reflex ares. Nicotine, before and after transection of the spinal cord, produces only local tremors in the trunk due presumably to its action on the anterior horn cells of the spinal cord.
In the salamander both nikethamide and caffeine produce a tonic type of seizure without clonic components. The extreme rigidity produced by caffeine seems to involve an action of this drug on the brain, since it is diminished considerably after a transection of the cord. Nikethamide does not produce extreme rigidity, but unlike caffeine it produces a striking regularity of slower waves in the electrical record.
Time of onset and duration of side effects as manifested by neurological tests is summarized graphically.
Footnotes
- Received January 15, 1958.
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