Inhibition of experimental seizures in canines by repetitive vagal stimulation.
Repetitive electrical stimulation of the canine cervical vagus nerve interrupts or abolishes motor seizures induced by strychnine and tremors induced by pentylenetetrazol (PTZ). Tremors were defined as rhythmic alternating contractions of opposing muscle groups, exerting much less force than seizure contractions. Seizures were induced by injection boluses of strychnine or PTZ at 1- to 4-min intervals until sustained muscle activity was observed electromyographically (EMG). Vagal stimulation terminated seizures in 0.5-5 s. There were prolonged periods with no spontaneous EMG activity after stimulation. The period of protection was approximately four times the stimulation period. The antiseizure actions of vagal stimulation were not altered by transection of the vagus distal to the stimulating electrode. Optimal stimulus parameters were estimated: strength, approximately 20 V (electrode resistance 1-5 omega); frequency 20-30 Hz; duration, approximately 0.2 ms. These data suggest that the antiseizure effects derive from stimulation of small-diameter afferent unmyelinated fibers in the vagus nerve. These results may form the basis of a new therapeutic approach to epilepsy.
Zabara
J
J
Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy / Q000379:methods; D004576:Electromyography; D004827:Epilepsy / Q000628:therapy; D005260:Female; D006801:Humans; D008297:Male; D010433:Pentylenetetrazole; D012640:Seizures / Q000139:chemically induced / Q000517:prevention & control*; D013331:Strychnine; D014202:Tremor / Q000139:chemically induced / Q000517:prevention & control; D014630:Vagus Nerve / Q000502:physiology*
D013331:Strychnine; D010433:Pentylenetetrazole