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Cerebrospinal fluid (CSF) transient responses induced by hypercapnia

Thesis/Dissertation ·
OSTI ID:6062199
CSF transient responses to CO/sub 2/ inhalation were measured before and after facilitated perfusate flow through subarachnoid spaces of anesthetized cats during ventriculocisternal perfusion with artificial CSF containing /sup 14/C-dextran. Convective mixing of perfusate in subarachnoid spaces was augmented while infusion constant, either by impeding cisternal efflux of perfusate by raising the cisternal outflow cannula (high CSF pressure), or by preventing CSF outflow by clamping the cisternal outflow cannula (stopflow; S-F). CSF transients were also measured before and after systemic administration of phenoxybenzamine (PBZ) in order to evaluate the contribution of sympatho-adrenergic activity to craniospinal CSF redistribution and mixing. Results from high CSF pressure and S-F experiments indicate that unequilibrated CSF contributes significantly to the reduced tracer concentration in CSF volume (Vd) since SCF effluent tracer concentration (Cd) was decreased after subarachnoid facilitated flow. Further, results from S-F studies indicate that at least 50% of Cd is due to craniospinal fluid redistribution, a process which, along with CSF outflow transients, was unaffected by PBZ. Conversely, PBZ administration decreased steady state SCF formation and absorption through alpha-mediated cerebrovascular responses and/or through beta-adrenoceptor inhibition of metabolism of CSF secretory epithelium.
Research Organization:
Michigan State Univ., East Lansing (USA)
OSTI ID:
6062199
Country of Publication:
United States
Language:
English