Affiliation:
1. Division of Neurobiology, Department of Neurology and Neuroscience, Cornell University Medical College, New York, New York, U.S.A.
Abstract
Laser–Doppler flowmetry was used to continuously monitor cortical CBF during electrical stimulation of the fastigial nucleus (FN). Rats were anesthetized with isoflurane (0.75–5%), paralyzed, and artificially ventilated. The LDF probe was placed over a target region of the parietal cortex through a burr hole. The hypertension associated with FN stimulation was prevented by spinal cord transection at C1 with arterial pressure maintained by i.v. infusion of phenylephrine. After cord transection, CBF changed linearly with changes in arterial pco2 ( r = 0.93; n = 23). FN stimulation (50–100 μA, 50 Hz, 1 s on/1 s off) produced sustained increases in CBF that developed slowly, reaching 50% of maximum within 24 ± 1 s of stimulation (n = 17). After stimulation, CBF returned to baseline gradually within a time period (84–540 s) proportional to the duration of the stimulation ( r = 0.93; n = 15). The CBF response was stimulus frequency and intensity dependent, was elicited only from restricted sites in FN, and was abolished by atropine (1 mg/kg, i.v.) or pentobarbital (30 mg/kg, i.v.). The slow temporal profile of the cerebrovasodilation is compatible with the hypothesis that in cerebral cortex local neurons mediate the vasodilation by interstitial release of vasoactive agents rather than by a direct action of neural processes on blood vessels. LDF is an effective technique for monitoring phasic change in CBF and may be useful in studies of the intrinsic neurogenic control of the cerebral circulation.
Subject
Cardiology and Cardiovascular Medicine,Clinical Neurology,Neurology
Cited by
74 articles.
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