engleski

The investigation of CSF formation by ventriculoaqueductal perfusion method in cats.

 Objectives The method of perfusion the cerebrospinal fluid (CSF) spaces by arteficial CSF (aCSF), containing a marker of large molecular weight, is used to calculate net CSF formation (Heisey et al. 1962). To evaluate this indirect method we have developed a direct ventriculo-aqueductal perfusion method for measurement of CSF formation (Figure 1.) assuming that inflow rate should be smaller than outflow rate if net CSF formation in ventricles occurs.  Metods In chloralose anaesthetized cats the aqueduct of Sylvius was approached via transcerebellar route and cannulated so that outflow of this plastic cannula was positioned extracranially, and therafter the skull was hermetically closed. Both lateral ventricles were cannulated: one cannula was used for infusion of aCSF containing blue dextrane (m.w. 2 millions) and the other one for measurement of CSF pressure.  Results During ventriculo-aqueductal perfusion at rate of 12.96  l/min at normal CSF pressure, the outflow rate from aqueductal cannula did not differ significantly from inflow rate suggesting that formation and absorption rates of CSF in ventricles were equal as we recently suggested (Orešković et al. Neurosci.Lett. 327: 103, 2002).(Figure 2. and Table 1.)) However, when dilution of blue dextran in outflowing perfusate was used for calculation of CSF formation, a net formation of 5  l/min was obtained. Furthermore, in euthanasied cats net formation of CSF is obtained by this indirect method but not by our direct method (Figure 3.)  Conclusion Our results indicate that perfusion method with dilution of marker substance in outflowing perfusate is not reliable and that data obtained by this method sholud be reevaluated.

CSF; hydrocephalus; intracranial pressure

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