[Effect of stimulation of the medullary reticular formation on brain water content in cold injured brain].
Recently it has been reported that stimulation of the medullary reticular formation (MORF) directly decreased the cerebral vasomotor tonus by intrinsic pathways of the central nervous system and resulted in increases in the cerebral blood volume (CBV) and intracranial pressure (ICP). Decreased cerebral vasomotor tonus has been postulated to enhance water movement from vascular cavity to the brain tissue. So this study was carried out to investigate the effect of stimulation of MORF on brain water content in cold injured brain, which has been confirmed to have a similar pathophysiological nature to cerebral contusion. Experiments were conducted on 28 cats. The cold injury was inflicted by applying a freezing prove of -50 degrees C for 1 minute directly on the dura. 17 hours after cold injury, animals were divided into 4 groups, i.e. Group I: cold lesion only, Group II: electrical stimulation of MORF (1 msec, 10 V, 50 Hz) for 10 minutes, which was repeated 4 times with 5 minutes interval, Group III: the same stimulation of MORF for 40 minutes as Group II, with spinal cord transection at C-2 level before the stimulation to eliminate vasopressor response, Group IV: administration of Angiotensin II for 60 minutes to elevate blood pressure at the same level as observed during the stimulation. In each group, 18 hours after making lesion, the brain was removed and water content was determined by specific gravimetric technique and expressed as percent g water/g tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
Ogawa
T
T
Department of Neurological Surgery, Kagawa Medical School, Japan.
D000818:Animals; D001794:Blood Pressure; D001834:Body Water / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D001930:Brain Injuries / Q000378:metabolism / Q000503:physiopathology*; D002199:Capillary Permeability; D002415:Cats; D002560:Cerebrovascular Circulation; D003080:Cold Temperature / Q000009:adverse effects*; D004558:Electric Stimulation; D007427:Intracranial Pressure; D008526:Medulla Oblongata / Q000503:physiopathology*; D012154:Reticular Formation / Q000503:physiopathology*; D014664:Vasodilation