Role of Norepinephrine in the Brain in the Blood Pressure Response to Raised Intracranial Pressure

ABSTRACT

1. The intracranial pressure (ICP) was raised by the extradural balloon method in urethane-anesthetized rabbits, and change of the arterial blood pressure (BP) with change of ICP was studied. 2. In the control rabbit group raising ICP resulted in marked increase in BP. 3. In the reserpine-treated group raising ICP did not induce the increase in BP but the decrease in BP. 4. In the tetrabenazine-treated group raising ICP did not cause change in BP. 5. After the administration of norepinephrine through the lateral ventricle to the reserpine-treated and tetrabenazine-treated rabbits, raising ICP resulted in marked increase in BP. 6. These results indicate that the existence of norepinephrine in the brain is essential for the BP increase by raising ICP.