DYSFUNCTION OF THE MEDULLARY CARDIOVASCULAR CENTER MAY CAUSE ACUTE SPINAL-CORD SWELLING

Acute brain swelling is well known to be acute vasodilatation of cereb ral vessels and sometimes results from brain injury. One of the causes of acute brain swelling may be disturbance of central control mechani sms of cerebral vessels. However, the presence of acute spinal cord sw elling is little noticed. We present here a possibility that acute spi nal cord swelling may be occur following the dysfunction of the cardio vascular center of the medulla. In urethane-anesthetized, paralyzed an d artificially ventilated rats, the neurons in the rostral ventrolater al pressor area (VLPA), origin of the sympathetic nerve activities in the brain stem, were chemically stimulated by microinjection of L-glut amate and the spinal cord blood flow (SCBF) was determined using label ed microspheres. The SCBFs of cervical, thoracic, and lumbar cord decr eased significantly from 27 +/- 3 (mean +/- S.E.M.) to 20 +/- 2 (p < 0 .01), from 22 +/- 1 to 17 +/- 2 (p < 0.05), and from 41 +/- 5 to 26 +/ - 3 (p < 0.05) ml . min-1 . (100 g)-1, respectively (n = 12). The spin al cord vascular resistances (SCVRs) of cervical, thoracic, and lumbar cord increased significantly from 3.7 +/- 0.4 to 5.0 +/- 0.6 (p < 0.0 5), from 4.2 +/- 0.2 to 5.9 +/- 0.7 (p < 0.05), and from 2.5 +/- 0.2 t o 3.8 +/- 0.4 (p < 0.05) mmHg per [ml . min-1 . (100 g)-1], respective ly (n = 12). These results suggest that the neurons within the VLPA ma y play a role in the control of spinal cord circulation. There is a po ssibility that the dysfunction of the VLPA may cause acute spinal cord swelling.