Acute effect of glycerol on net cerebrospinal fluid production in dogs

The effect of glycerol administration on cerebrospinal fluid (CSF) formation in dogs was studied by means of a ventriculocisternal perfusion technique. Net CSF production rate decreased after oral administration of glycerol (3 gm/kg) from a baseline level of 42.33 +/- 6.68 microliter/min (mean +/- standard error) to a trough of 10.33 +/- 4.88 microliter/min at 90 minutes after administration (p less than 0.025). Serum osmolality concomitantly increased from a baseline value of 296 +/- 2.83 to 309 +/- 4.7 mOsm/kg H2O at 90 minutes. The mean percentage change in CSF production inversely correlated to the mean percentage change in serum osmolality, r = -0.85. Thus, glycerol administration decreases net CSF formation, and this effect may be related in part to the rise in serum osmolality.