Intravesical Ethanol as Quantitative Measure of Bladder Hyperpermeability

Abstract

Bladder surface hyperpermeability may be a factor in the etiology of interstitial cystitis (IC). We evaluated the intravesical instillation of ethanol as a quantitative measure of bladder hyperpermeability in an experimental model in male New Zealand White rabbits. In two study groups (N = 4 each), the glycosaminoglycan (GAG) layer on the bladder surface was disrupted via a 10-minute exposure to 10% protamine sulfate (PS). The study groups then underwent bladder instillation 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 blood was sampled, and the ethanol concentration was determined by mass spectrometry. Study group animals were sacrificed after blood sampling. Control animals were sacrificed at 2 weeks and 4 weeks for histologic examination of the bladder. The blood alcohol concentration was 0 in the control animals exposed 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 examination of bladder tissue revealed no ethanol-induced abnormalities in the control animals. Intravesical instillation of 10% and 20% ethanol is a safe and reliable quantitative measure of bladder hyperpermeability in an animal model. Clinical trials are ongoing to evaluate the utility of the intravesical ethanol test for diagnosing IC and monitoring the response to therapy.