Rates of Formation and Absorption of Cerebrospinal Fluid in the Very Young Calf

Abstract

Ventriculocisternal perfusion (VCP) was successfully performed on four of seven pairs of calves ranging in age from 3 to 10 weeks. One calf of each pair was perfused at its initially determined intraventricular pressure and the other at 200mm greater than its initial pressure. Linear regressions of bulk flow, bulk absorption, and formation, in grams per minute, Y1, on the imposed VCP pressure in millimeters of synthetic cerebrospinal fluid (CSF), X1, were respectively, Y1 = .02−.00183 X1 (±.07), Y1 = .14 + .00168 X1 (±.06) and Y1 = .16−.00014 X1 (±.01). Passive diffusion of creatinine across the ependymal lining of the ventricles averaged .06 ±.03 g/min and the volume of distribution of inulin (VDIn) equaled 12.1±3.6g. In comparing these statistics to those previously reported for 20-week-old calves, no significant differences were observed in the responses of bulk flow and bulk absorption to increases in VCP pressure. On the other hand, the average rates of CSP bulk absorption, CSF formation, and VDIn were less for the younger animals of the present experiment.