Some biochemical constituents in serum, cerebrospinal fluid, and aqueous humor of vitamin A deficient Holstein calves.

Summary Sixteen male Holstein calves previously raised to 63 days of age on a limited whole milk, limited starter, and ad libitum chopped alfalfa hay ration were fed a vitamin A depletion ration until their plasma vitamin A averaged 8.3 ± 2.2 γ per 100 ml. Each calf was then fed for a 16-wk. period one of four carotene intakes, 16 or 24 γ per pound of live weight per day, to provide marked increases in cerebrospinal fluid pressure, 32 γ, to provide slight elevation in pressure, or 40 γ, to provide no elevation. Terminal cerebrospinal fluid pressure decreased with increasing intakes of carotene, apparent intraocular (scleral) pressure exhibited no consistent change, and plasma and liver concentrations of carotenoids and vitamin A increased. Of the biochemical constituents studied, no trends with carotene intake were observed for serum, and only potassium of cerebrospinal fluid decreased slightly; whereas, for aqueous humor, sodium was higher in the calves fed the 16-, 24-, and 32-γ carotene intakes, potassium increased with an increase in carotene intake, chloride decreased, and osmotic pressure was greater in calves fed the 16-, 24-, and 32-γ carotene intakes than in those fed the 40-γ intake. These results do not directly explain the increased cerebrospinal fluid pressure or change in aqueous humor composition occurring in vitamin A deficiency. However, the data pertaining to cerebrospinal fluid suggest either an overproduction or underabsorption of fluid (without change in the concentration of the constituents in serum or cerebrospinal fluid), resulting in greater volume within the restricted subarachnoid space and ventricles of the central nervous system.