Abstract
The blood-pressure response during cerebral anæmia was analyzed by Pike, Guthrie and Stewart a number of years ago. Recently Winkin in studying some of the nervous factors involved in the cardio-vascular changes which take place during cerebral anæmia observed that after repeated occlusions of the head arteries for short periods, the curve of the anæmic rise may become dissociated into two distinct parts.
The question was raised by Winkin whether the second part of this anæmic rise may not be due to increased availability of some product of adrenal activity which the “cardio-vascular relations found in the mammalian organism under extreme conditions of stress” would call forth. With this in mind, we have carried out a series of experiments on cats and rabbits when:
1. The adrenal glands are tied off, or excised during an acute experiment.
2. The adrenal veins are clipped.
3. The remaining adrenal is excised (one having been previously excised and the animal allowed to recover).
4. One adrenal is excised and the other denervated (and the medulla of it curetted out or a large part of the remaining gland excised in addition to denervation) and the animal allowed to recover.
5.: Both adrenals are excised (rabbit) and the animal allowed to recover.
In cases 3, 4, and 5 the animals were operated upon from two to four weeks before the acute experiments were performed. The technique of the acute experiment was that devised by Stewart, Guthrie, and Pike in which the arteries are secured as they emerge from the thorax. It is well known that in the cat and rabbit, when the carotid and subclavian arteries (proximal to the origin of the vertebrals) are occluded, circulation to the head is completely interfered with and cerebral anaemia with the attendant anxmic rise of Mood-pressure ensues rapidly.
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