Rates of Formation and Absorption of Cerebrospinal Fluid in Mild Chronic Bovine Hypervitaminosis A

Abstract

Abstract Ventriculocisternal perfusion (VCP) of eight control and six chronic hypervitaminotic A Holstein male calves was conducted to estimate the rates of formation \( V ˙ f \) and bulk absorption (inulin clearance, C In ) that are associated with the lower cerebrospinal fluid (CSF) pressures observed in experimental hypervitaminosis A. The control and hypervitaminotic A calves received 108 and 10,800 μ g of retinol (as vitamin A acetate)/kg live wt/day and were 147 and 146±2 days of age, weighed 103 and 89±10kg with plasma vitamin A concentrations of 29.6 and 125.0μg/100ml, respectively. Initial intraventricular (IV) CSF pressures relative to the site of IV cannulation were -13 and -55mm of synthetic CSF for the control and hypervitaminotic A groups, respectively. V ˙ f , in grams per minute, was unaffected by the imposed perfusion pressure and equalled 0.342±0.059 for the control calves and 0.236±0.059 for the hypervitaminotic A calves. Regression of C In in g/min on imposed perfusion pressure (0 or +200mm of synthetic CSF) relative to the initial IV pressure, X, for the control calves was: C In = 0.324 + 0.00159 X±0.095 and for the hypervitaminotic A calves, C In = 0.322 + 0.00212 X±0.095. The lower CSF pressure of the chronic hypervitaminotic A calf is apparently due in part to a reduced rate of formation of CSF and possibly to a decreased resistance to bulk absorption.