Abstract

The effects of epinephrine, norepinephrine and related substances on electrically induced seizures were investigated in cats by simultaneous recordings of blood pressure and EEGs. The parameters of stimulation for submaximal electro-shock which would elicit convulsive afterdischarges of reproducible strength and duration were determined.

1. Epinephrine and norepinephrine in doses of 1 to 10 microgm./kgm. markedly prolonged seizure duration and shortened the period of cortical extinction.

2. Endogenous epinephrine released from the adrenal medulla similarly enhanced cortical afterdischarge.

3. Amphetamine produced prolongation of cortical afterdischarge while ephedrine, Neo-Synephrine and Pitressin, in equipressor doses increased seizure duration only slightly. Acetyicholine and histamine depressed the cortical response to electroshock.

4. Since glucose, ACTH, and cortisone failed to prolong seizure duration it is unlikely that epinephrine acts by release of these substances.

5. Evidence of the relative independence of blood pressure variations and seizure duration suggests that epinephrine prolongs cortical afterdischarge and shortens the period of cortical extinction by a direct action on the central nervous system.