Neurohumoral Transmission of the Pressor Response to Intracranial Compression

Abstract

After acute intracranial compression in the chick or rabbit, there is a delay before the pressor response is seen. This lag appears to be related to the rate of movement of the circulating blood. In hypothermia the lag is prolonged to approx. the same degree as is the circulation time. The route of the response to intracranial pressure apparently involves the medulla oblongata and the sympathetic chain, operating through the release of graded amts. of pressor material into the systemic venous capillaries. After a complete circulation, arrival of this material at the systemic arterioles brings on the pressor effect. The pressor material released by intracranial compression has produced effects similar to those caused by norepinephrine. It is blocked by Dibenamine and by benzodioxane. Depression (reversal) of the blood pressure was seen occasionally after intracranial compression, especially in benzodioxane-treated animals. Tetra-ethylammonium did not block the pressor response. The substance apparently arises from sources extrinsic to the adrenal gland and the abdominal viscera. The possible significance of such a pressor system on the blood pressure regulation apparatus is discussed.