Intravesical ethanol as quantitative measure of bladder hyperpermeability

Background and Purpose: Bladder surface hyperpermeability may be a factor i n the etiology of interstitial cystitis (IC). We evaluated the intravesical instillation of ethanol as a quantitative measure of bladder hyperpermeabi lity in an experimental model in male New Zealand White rabbits. Materials and Methods: In two study groups (N = 4 each), the glycosaminogly can (GAG) layer on the bladder surface was disrupted via a 10-minute exposu re to 10% protamine sulfate (PS). The study groups then underwent bladder i nstillation of 10% (group 1) and 20% (group 2) ethanol. The control groups underwent bladder instillation of either 10% (N = 2) or 20% ethanol (N = 2) without exposure to PS. Ten minutes after ethanol instillation, venous blo od was sampled, and the ethanol concentration was determined by mass spectr ometry. Study group animals were sacrificed after blood sampling. Control a nimals were sacrificed at 2 weeks and 4 weeks for histologic examination of the bladder. Results: The blood alcohol concentration was 0 in the control animals expos ed to 10% or 20% ethanol, 14.5 +/- 2.2 ng/dL in the 10% ethanol study group , and 25.6 +/- 3.6 ng/dL in the 20% ethanol study group. Histologic examina tion of bladder tissue revealed no ethanol-induced abnormalities in the con trol animals. Conclusion: Intravesical instillation of 10% and 20% ethanol is a safe and reliable quantitative measure of bladder hyperpermeability in an animal mod el. Clinical trials are ongoing to evaluate the utility of the intravesical ethanol test for diagnosing IC and monitoring the response to therapy.