Abstract
The relation between the cerebrospinal pressure and the circulation was investigated on rabbits anaesthetized with urethane. The fluid pressure at the Cisterna cerebellomedularis was measured by Harada's method in which the pressure measured with Hg-manometer was calculated in terms of water-pressure and drawn on a kymograph. To observe the cerebral blood flow, the modified “thermocouple method” of Takenaka was used. The results obtained : (1) The cerebrospinal fluid pressure measured in 450 rabbits varied between 55-89 mm water, the majority were between 65-85 mm water. (2) There is no alternation in the brain circulation when the pressure is raised to 650 mm water or is lowered to-120 mm water. (3) A rise or fall of the cerebrospinal pressure does not influence the amplitudes of the pressure curve. (4) Adrenaline at first increases the pressure as well as the blood flow in the brain and later it decreases them, although they differ in the extent and duration after various doses (See Fig. 1). (5) Inhalation of ether increases the cerebral blood flow and the cerebrospinal pressure. (6) Barium chloride causes a transient increase of the pressure and blood flow and then it decreases markedly the blood flow while only a slight fall of the pressure occurs (Fig. 2). (7) Acetylcholine increases the blood flow and the pressure (Fig. 3). (8) The changes in the blood flow measured with the thermocouple method is revealed a short time after the pressure changes. (9) The extent of a rise.of the pressure is proportionate to an increase of the blood flow, but it decreases out of proportion to the pressure.
