Spreading Depression in Rabbit, Cat and Monkey

Abstract

Rabbits, cats and monkeys show species difference in the consistency and frequency with which spreading depression (SD) can be elicited during the first hours after exposure of the cortex. In the rabbit SD can be produced consistently at 6–10-minute intervals. In most of the preparations of the cat it is also possible to produce a series of SDs when using a longer interval (15–20 min.) between stimulations. Only rarely is it possible to obtain in the monkey a series of SDs even when long intervals are interjected between stimuli. However, the majority of preparations responded at least once with a SD. It has been possible to lead off SD in rabbits and cats with extradural electrodes implanted in the skull 5–7 days earlier. These electrodes were in most instances flush with the dural surface of the skull, resting on the undamaged dura. In the rabbit photo-Metrazol stimulation can produce SD which also has been recorded with the implanted electrodes. Since there is no reason to believe that the cortex in these latter experiments was damaged or in any other way abnormal, the conclusion was drawn that normal cortex can exhibit spreading depression.