The Effect of PDE 4 Inhibitor on Urinary Bladder Function in Normal Rats

ABSTRACT

PURPOSE: PDE 4 inhibitor is known to be a bladder relaxant. In this study, the effects of PDE 4 inhibitor on the urinary bladder function were evaluated in vivo experiment. We postulated that PDE 4 inhibitor of appropriate concentration might be helpful in the treatment of overactive bladder. MATERIALS AND METHODS: Fifteen Spraque-dawley female rats, weighing approximately 250~300 mg, were used for this study and divided into three groups. PDE 4 inhibitor 486,051 was administrated to each rat by different drug concentrations(0.5 mg/kg, 1 mg/kg, 5 mg/kg). Cystometrogram(CMG) was performed before and 20~60 minutes afterV), bladder capacity(BC), maximal bladder voiding contraction pressure(MVP), intercontrac drug application considering first voiding. Cystometric parameters investigated were voided volume(VV), residual volume (RV), bladder capacity(BC), maximal bladder voiding contraction pressure(MVP), intercontraction interval(ICI). Mean blood pressure was monitored in all rats. RESULTS: PDE 4 inhibitor of 0.5 mg/kg increased the intercontraction interval but not the bladder capacity significantly. PDE 4 inhibitor of 5 mg/kg increased the bladder capacity significantly, but did not show the increased intercontraction interval compared to other groups, and showed the greatest increased residual volume among three groups. PDE 4 inhibitor of 1 mg/kg showed the most increased intercontraction interval and the bladder capacity, and the least decreased voided volume and maximal bladder voiding contraction pressure change. CONCLUSION: PDE 4 inhibitor of different concentrations affects cystometric parameters variably by bladder smooth muscle relaxant. PDE 4 inhibitor of appropriate concentration may be helpful in the treatment of overactive bladder. PDE 4 inhibitor, at the concentration of 1 mg/kg, increased the bladder capacity and intercontraction interval most significantly. This study may provide an important basic data in the future when drug effects were assessed in variable animal models of overactive bladder, etc. However, main limitations of drug use are the increase of residual urine and the decrease of blood pressure. Therefore more bladder specific drug is needed.