Assessment of murine bladder permeability with fluorescein: Validation with cyclophosphamide and protamine

Objectives. Bladder hyperpermeability should result in elevated blood level s of intravesically administered agents. Reabsorption from a hyperpermeable bladder should result in prolonged urinary excretion of an agent after par enteral administration. To test these hypotheses, urinary clearance and pla sma levels of sodium fluorescein (NaF) were measured in mice before and dur ing cyclophosphamide (CYP) and protamine-induced hemorrhagic cystitis. Methods. To measure the plasma uptake of NaF from the bladder, 10 mg/mL NaF was instilled, either by catheter or retrograde urethral infusion, 15 minu tes before retro-orbital or ventricular sampling. The plasma levels were me asured 24 hours and 14 days after exposure to CYP 300 mg/kg or 15 minutes a fter instillation of protamine 10 mg/mL. Hourly urine concentrations were m easured immediately after intraperitoneal administration of 10 mg/kg NaF. P retreatment samples were compared with those obtained 24 hours after intrap eritoneal administration of 300 mg/kg CVP. Results. Urinary NaF excretion was delayed in CVP-exposed mice. A bi-expone ntial model provided an appropriate fit of the data, both before and after CYP administration. The plasma levels of NaF were significantly elevated at 24 hours and 14 days after CYP exposure when sampled by ventricular nick o r retro-orbitally. The median concentration of fluorescein in the protamine -treated mice was significantly higher than in the control mice. Conclusions. Fluorescein can be used to measure alterations in bladder perm eability after bladder mucosal injury in mice. Urinary excretion of NaF is a bi-exponential process that is delayed after bladder mucosal injury, pres umably because of increased mucosal permeability and resorption from the ur ine into the bloodstream. UROLOGY 58: 113-118, 2001. (C) 2001, Elsevier Sci ence Inc.