Pharmacologic manipulation of the flushing action of cerebrospinal fluid. Effect on CSF diatrizoate levels.

The continual production and absorption of cerebrospinal fluid (CSF) provides for the dilution and removal of potentially toxic substances from the central nervous system (CNS). This study quantified changes in the CSF concentration of diatrizoate following pretreatment with various drugs that alter CSF production. Adult rats, pretreated with one of ten drugs or normal saline (control) and anesthetized, received sodium diatrizoate (2 mL/kg, IV). Blood and CSF were sampled 2 hours later, and the diatrizoate concentrations were measured. Serum diatrizoate levels in the control group averaged 144.3 micrograms/mL. There were no significant differences in serum levels between control and pretreated groups. The CSF diatrizoate concentration in the control group averaged 10.8 micrograms/mL. Pretreatment with acetazolamide, ritodrine, or probenecid resulted in a significant increase in the CSF concentration, to 24.7 micrograms/mL or 228% of control in the case of acetazolamide. Pretreatment with salicylate, carbachol, or aminophylline resulted in significantly lower CSF diatrizoate levels than control; 3.2 micrograms/mL (30% of control) for carbachol. Digoxin, furosemide, dibutyryl cAMP, or dexamethasone pretreatments had no significant effect on CSF diatrizoate concentrations. Thus, a wide range of drugs may significantly alter the concentration of diatrizoate in the CNS. Drug-induced changes in the rate of CSF production may be responsible for this action.