The effect of pentoxifylline on detrusor muscle contractility after partial urethral obstruction in a rat model

Purpose: To evaluate the effect of pentoxifylline (PTX), a nonspecific type 4 phosphodiesterase inhibitor, on contractility of obstructed detrusor muscles. Methods: Sixty male Sprague–Dawley rats were randomized into three groups each containing 20 animals. The control groups included rats with induced BOO which received the solvent of PTX (drinking water), the sham group included rats with intact bladder outlet which received no treatment, and the treatment group was treated with PTX after induction of BOO. Four weeks after the operation and/or treatment, animals were killed and detrusor muscle of them was evaluated for contractility parameters. Results: Carbachol-induced detrusor muscle tension increased proportionally with concentration of carbachol. The maximum carbachol-inducing muscle tension was significantly higher in the sham group in comparison to the rats with BOO (P < 0.001). In the latter group, PTX treatment caused no significant improvement in the maximum carbachol-induced muscle tension compared to the control group. However, no significant difference was observed among the study groups concerning the pEC50 of carbachol (5.77 ± 0.10, 5.96 ± 0.64, and 5.84 ± 0.17 in the sham, control, and treatment groups, respectively). BOO resulted in a great but statistically non-significant (P = 0.074) decrease in electrically induced bladder contraction in comparison with the sham group. Treatment with PTX reversed this effect significantly (P = 0.023), and the obtained values were almost the same as those of the sham group. Conclusion: PTX improved detrusor muscle contractions in responses to electric stimulation in obstructed bladder. In contrast, no improvement was detected in contractile responses to the carbachol stimulation.