THE CEREBRAL CIRCULATION XXXIV. THE ACTION OF NARCOTIC DRUGS ON THE PIAL VESSELS

¹ From the Department of Neuropathology, Harvard Medical School, and the Neurological Unit, Boston City Hospital

1. The removal of ether from cats previously etherized was followed by a constriction of the pial arteries, a decrease in cerebrospinal fluid pressure, and in most cases by a decrease in systemic blood pressure. Inhalation of ether in post-ether cats caused a dilatation of the pial arteries, an increase in cerebrospinal fluid pressure and an increase in blood pressure.

2. The inhalation of chloroform in post-ether cats caused an increase in the diameter of the pial arteries, a rise in cerebrospinal fluid pressure and a drop in blood pressure.

3. The subcutaneous injection of morphine in doses up to 2.2 mgm. per kilogram body weight in post-ether cats caused no appreciable changes in the diameter of the pial arteries, in the cerebrospinal fluid pressure and in the systemic blood pressure. The subcutaneous injection of larger doses of morphine (2.4 to 46 mgm. per kilogram) caused a dilatation of the pial arteries, an increase in cerebrospinal fluid pressure, and a drop in systemic blood pressure.

4. The intraperitoneal and intravenous injection of amytal in post-ether cats caused a dilatation of the pial arteries, a rise in cerebrospinal fluid pressure and a decrease in systemic blood pressure.

5. The intraperitoneal and intravenous injection of sodium luminal in post-ether cats caused a dilatation of the pial arteries, an increase in cerebrospinal fluid pressure and, a decrease, often transitory, in systemic blood pressure.

6. The rectal and intraperitoneal injection of a solution of avertin crystals in post-ether cats caused a decrease in the diameter of the pial arteries, a decrease in the cerebrospinal fluid pressure, and a drop in the systemic blood pressure, which was often transitory.