Abstract
The response of the brain vessels to i.a. infused epinephrine, norepinephrine and isoprenaline was evaluated. The experiments were performed on isolated canine brains which were perfused from donor dogs. Total venous outflow and perfusion pressure in the circle of Willis were monitored continuously and total cerebral vascular resistance (CVR) was calculated. Dose response curves were obtained for these three amines, ranging from 0.001–10 μg: The effects of the amines on CVR are influenced by their effects on extracerebral vessels and by the cerebral autoregulation. After elimination of the calculated autoregulatory influence the true catecholamine effects on CVR are about 50% of the original effects. A comparison of equimolar doses (1 nmol) of the three amines after infusion of α-and β-blocking agents showed: These results are discussed in relation to the possible influence of non-cerebral tissues including neurocranium and meninges. It is felt that these sources of contamination cannot account for the vasomotor responses and that, consequently, both α-and β-adrenergic activity of the cerebral vessels of the dog has been demonstrated.
Published Version
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