Medullary Cardiovascular Center and Acute Brain Swelling

Acute brain swelling is reported to be due to acute vasodilatation of cerebral vessels. One of the causes of acute brain swelling may be disturbance of central control mechanisms of cerebral vessels. It has been reported that the anatomical location of the area which controls cerebral circulation is related to the area which controls systemic circulation. However, the role of the cardiovascular center on cerebral circulation has not been clear. The present study was, therefore, undertaken to examine the effects of chemical stimulation of the medullary cardiovascular center [nucleus tractus solitarius (NTS), ventrolateral depressor area (VLDA), and ventrolateral pressor area (VLPA)] on cerebral circulation. In anesthetized, paralyzed and artificially ventilated rats, the neurons in the NTS, VLDA, and VLPA were chemically stimulated and the cerebral blood flow (CBF) was determined using labeled microspheres. The CBF decreased significantly and the cerebrovascular resistance (CVR) increased significantly by chemical stimulation of the NTS, VLDA, and VLPA. These results suggest that the neurons within the NTS, VLDA, and VLPA control cerebral vessels vasoconstrictively. There is a possibility that the dysfunction of the NTS, VLDA, and VLPA may cause acute brain swelling.