Rates of Formation and Absorption of Cerebrospinal Fluid in Bovine Hypovitaminosis A

Abstract

Ventriculocisternal perfusion (VCP) was used to determine the rates of bulk absorption (inulin clearance, CIn) and formation (Vf) of cere-brospinal fluid (CSF) in 9 hypovitaminotic A and 10 vitamin A adequate calves. The average intraventricular CSF pressures were 374 and 54 mm of synthetic CSF for the deficient and adequate calves, respectively, with corresponding plasma vitamin A concentrations of 5 and 29 [mu]g/100 ml. Regressions of CIn and Vf, both in g/min, on perfusion pressure (-100, 0, or +200 mm of synthetic CSF relative to the initially determined CSF pressure), X, were, respectively, for the deficient and adequate calves: CIn = 0.258 + 0.00062X and CIn = 0.318 + 0.00111X (SD = 0.038); Vf = 0.312 - 0.99916X and Vf 0.328 - 0.00030X (SD = 0.034). The magnitude of the response to the induced VCP pressures was significantly less for CIn in the deficient calves, whereas, for Vf, differences were not significant. Thus, absorption of CSF is impaired in hypovitaminotic A calves.