Abstract
Whenever any central effects of catecholamine are studied, the possibility that the amines act indirectly by virtue of their effects upon cerebral blood vessels and flow merits some consideration. The effects of the amines upon these structures were the subjects of a number of research work since 1900's. As might be anticipated, there are many contradictory results in which adrenaline delates the cerebral vessels, constricts them, does both or does neither. Recently, Ingvar and Söderberg (1) have studied the effects of adrenaline and noradrenaline on cerebral flow in cat by measuring the rate of venous outflow of the cannulated superior sagittal sinus. They found that the intravenous adrenaline or noradrenaline produced an increase of the cerebral blood flow, apparently secondary to the pressor response, and that noradrenaline produced less increase of the flow than adrenaline, and also that the intracarotid injection of noradrenaline caused a brief cerebral vasoconstriction before the pressor effect by the amine manifested, whereas the same procedure of adrenaline caused no initial constriction.
Though there is no reason to assume that catecholamines act directly or indirectly on the specific mechanism in the brain, the present experiment was designed to elucidate the correlation between the mode of the cerebral vessels an.d the central sympathetic activity in response to the intravenously administered adrenaline or noradrenaline in the anesthetized dog following the technique of the cross circulation of their head (2). Recently, Polet and De Schaepdryver (3) have devised a modified method of the isolation of head circulation, in which the head circulation of the recipient is completely separated from that of the body with a maintenance of a normally functioning spinal cord.
