EFFECTS OF RESERPINE AND CHLORPROMAZINE ON THE VASOMOTOR CENTER IN THE MEDULLA OBLONGATA OF THE DOG

¹ Departments of Pharmacology and Anesthesiology, Coollgqe of Physicians and u gyeons, Columbia University, New York, N. Y.

The effect of reserpine and chlorpromazine on the medullary vasomotor mechanism was studied in cross-circulation experiments in dogs anesthetized with morphine-chloralose. The head of the recipient dog was completely isolated from its body except for the spinal cord and sometimes also the vagi, and was perfused by a donor dog. The presser response to electrical stimulation of the medullary vasomotor area was not modified or slightly exaggerated in 14 of 18 experiments when reserpine, 0.2 to 4 mg/kg, was given to the head circulation via the donor animal. In 17 of 20 experiments, this response was depressed by chlorpromazine, 0.1 to 2 mg/kg, similarly administered. It can be concluded that the hypotensive action of chlorpromazine, but not that of reserpine, may be partially explained by a depression of the medullary vasomotor mechanism.