Intracerebroventricular vasopressin reduces CSF absorption rate in the conscious goat

Cerebrospinal fluid (CSF) levels of vasopressin (AVP) are elevated in some disorders associated with raised intracranial pressure. We have previously demonstrated that intracerebroventricular infusion of AVP in the conscious goat leads to elevation of intracranial pressure by a mechanism independent of changes in arterial blood pressure or circulating neurohypophysial peptide concentrations. We have now examined the effect of increasing CSF AVP levels on CSF dynamics using the technique of ventriculo-cisternal perfusion in the conscious goat. Intracerebroventricular perfusion with 5 pmol/min AVP in artificial CSF did not alter CSF formation rate but significantly reduced CSF absorption rate (24% decrease; p less than 0.01), when compared with perfusion using artificial CSF alone. This AVP-mediated reduction in CSF absorption rate may represent increased resistance to resorption of CSF or may reflect the effect of raised intracranial pressure.