Abstract
Circulatory and respiratory changes by stimulation in the medulla oblongata were investigated in 36 dogs.
(1) The localization relating to the changes of blood pressure, heart beat and respiration was observed. The distribution of blood pressure and prespiratory response was generally in agreement with the findings of previous investigators.
(2) A fall in blood pressure was, as a rule, associated with a decrease in heart rate, and assumed to be caused by both cardioinhibitory and vasodepressor effects. Whereas, an elevation in blood pressure was occasionally associated with a decrease in heart rate. This paradoxical response seemed in part to be elicited by the reflex, but in part seemed by the direct cardioinhibitory and vasopressor effects.
(3) In dorsal vagal nucleus, the cardioinhibitory effect was obtained, but in part the cardioacceleration was also observed. This mechanism was discussed.
