EFFECTS OF STIMULATION OF THE SEPTAL AREA UPON BLOOD PRESSURE AND RESPIRATION IN THE CAT

Abstract

In 21 of 25 intact cats under chloralose a fall in blood pressure was elicited that outlasted the electrical stimulation of the septal area about 3-5 minutes; when a pure depressor reaction was present, it began gradually during the period of stimulation and was accentuated after the end of the stimulus; however, when respiratory changes were present the latency of the response was shorter. The fall in blood pressure sometimes was preceded by a slight pressor reaction, and in some cats the depressor effect was only observed after the end of stimulation. Several tests indicate that the depressor reaction is due most probably to an inhibition of vasoconstrictor and cardiac-accelerating fibers, but a role for vasodilator facilitation cannot be ruled out. The hypothesis is advanced that this reaction could be due either to nervous or to humoral mechanisms, or to both occurring simultaneously. The physiological meaning of this depressor effect if considered in relation to behavioral and sleeping functions of the septal area.