[The different vascular reactions of intact and ischemic brain to adrenergic exposures].

Electrical stimulation of the cervical sympathetic ganglion and norepinephrine increase the tonus of the cerebral vessels in intact animals. This points to the significant role of adrenergic mechanisms in regulation of blood circulation in the brain. Local ischemic affection of the brain removes the vasoconstrictor effects of stimulation of the cervical sympathetic ganglion and norepinephrine. Analysis by means of dihydroergotamine suggests that ischemia of the brain disturbs the property of alpha-adrenoceptors of the cerebral vessels to increase the tonus of the latter in response to adrenergic effects.