The effects of ventricular fluid osmolality on bulk flow of nascent fluid into the cerebral ventricles of XXXX .

@entity1133 @entity1219 @entity3791 @entity969 @entity28842 @entity468
The effects of ventricular fluid osmolality on the bulk flow of nascent fluid into the cerebral ventricles of anesthetized @entity468 was measured during ventriculocisternal perfusion. This nascent fluid consists of both cerebrospinal fluid (CSF) and fluid which results from an osmotic gradient between ventricular fluid and the blood and/or brain. Perfusions were carried out with both mock CSF and with solutions containing either @entity969 , @entity1133 , or @entity1219 . Differences between the normal bulk flow rate of nascent CSF and bulk flow rate measured during perfusion with anisotonic solutions were linearly related to corresponding differences in osmolality of the effluent fluid from the ventricles. The coefficients of somotic flow using @entity969 (0.231 mul/min per @entity28842 ) and @entity1219 (0.224) were similar, and greater than that using @entity1133 (0.156). During perfusion with @entity969 when effluent osmolality increased by 200 @entity28842 (63% of normal), bulk flow rate of nascent fluid increased by 50 mul/min (200% of normal). Flow was undetectable when the effluent osmolality was 190 @entity28842 (decrease of 135 @entity28842 ), although osmotically active particles continued to enter the ventricular system. Intravenous injection of @entity3791 reduced these coefficients to similar values of 0.0963 for @entity1219 , and 0.0955 for @entity1133 . In all experimental conditions no changes were found in cerebral water content. These results suggest that the increased bulk flow which occurs during perfusion with hypertonic solutions originates from the choroid plexus.
