Cerebrospinal fluid pressure of anaesthetized rats during intracerebroventricular infusion.

Increases in cerebrospinal fluid pressure (CSFP) were measured in the lateral ventricle in barbiturate anaesthetized male Sprague Dawley rats during intracerebroventricular (IVT) infusions into the contralateral ventricle. IVT infusions of isotonic artificial CSF (art-CSF) solutions at 10 and 38 microliters/hr increased mean CSFP from control preinfusion level of 3.6 cm H2O to 4.6 cm H20 (n.s.) and 5.2 cm H2O (p less than 0.01) respectively with CSFP appearing to attain equilibrium after 30-60 min of infusion. IVT infusion of hyperosmolar art CSF solutions (saccharide and salt solutions of approximate 1000 mOsm/kg) at 38 microliters/hr resulted in a larger increase of CSFP which equilibrated at 8.5 cm H2O (p less than 0.001) after 90 min of infusion. It is suggested that on the basis of CSFP measurements in these and other experiments cited that IVT infusions be run at infusion rates of less than 40 microliters/hr to ensure minimal physiological change.