Dependence of cerebrospinal fluid pressure and volume on the changes in serum osmolarity in cats.
OBJECTIVE
To study the effect of blood osmolarity on cerebrospinal fluid (CSF) volume and CSF pressure in cats.


METHODS
Three types of methods were used on anesthetized cats. The first, ventriculo-cisternal perfusion (12.96 μL/min) before and after i.v. application of 20% mannitol; the second, measuring the outflow of CSF by cisternal free drainage; and the third, measuring CSF pressure in the ventricles of an intact CSF system, with the second and third method being performed before and after the i.p. application of a hypo-osmolar substance (distilled water).


RESULTS
In the first group, the application of 20% mannitol led to a significantly reduced (p < 0.005) outflow volume (from 12.60 ± 0.29 to 0.94 ± 0.09 μL/min). In the second group, the outflow CSF volume significantly increased (p < 0.001) after the application of distilled water (from 18.8 ± 0.3 to 28.2 ± 0.7 μL/min). In the third group, after the application of distilled water, the CSF pressure also significantly increased (p < 0.05; from 8.3 ± 0.8 to 16.1 ± 0.14 cm H(2)O).


CONCLUSIONS
We conclude that changes in serum osmolarity change the CSF volume because of the osmotic gradient between the blood and all of the CSF compartments, and also that the change in CSF pressure is closely associated with changes in CSF volume.
Department of Pharmacology, University of Zagreb School of Medicine, Zagreb, Croatia.
Ivana
I
Jurjević
Jurica
J
Maraković
Darko
D
Chudy
Ivona
I
Markelić
Marijan
M
Klarica
Ana
A
Froebe
Darko
D
Orešković
D000818:Animals; D002415:Cats; D002555:Cerebrospinal Fluid / Q000502:physiology*; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D008297:Male; D008353:Mannitol / Q000008:administration & dosage; D009994:Osmolar Concentration; D010477:Perfusion; D044967:Serum; D013997:Time Factors
D008353:Mannitol