Effects of Ethanol Oral Administration on Detrusor Muscle and Micturition in the Male Rat

Kim, Jung Hyun; Jung, Hee Chang; Park, Tong Choon

Abstract

PURPOSE: Acute ethanol intoxication is known to be a high risk factor for urinary retention among patients with benign prostatic hyperplasia. In this study, the effects of ethanol on rat bladder function were evaluated with in-vivo and in-vitro experiment. In addition, the effect of calcium on inhibitory action of ethanol was investigated with bladder muscle strips.
MATERIALS AND METHODS
In in-vivo study, two sets of experiments were performed in the male rat. In the first set, infusion cystometry was performed under anesthesia with oral adminstration of ethanol and voided volume, voiding pressure and residual urine were measured. In the second set of experiments, the bladder and the urethra were completely separated by means of ligation between the bladder neck and the proximal urethra. A simultaneous recording of the isovolumetric bladder contraction and proximal urethral relaxation pressure was performed. In in-vitro study using the bladder body muscle strips, the contractile responses were induced by bethanechol(10-3M) in the Krebs, solution containing different calcium concentrations. Various concentrations of ethanol were added in the bath and the contractile responses were measured.
RESULTS
In in-vivo study following oral adminstration of ethanol, the cystometrographic findings showed that voiding pressure and volume were decreased, however, residual urine volume was significantly increased, and the proximal urethral relaxation pressure was not changed significantly. In in-vitro study, the removal of extracellular calcium significantly reduced the bladder contractile response to bethanechol. The high level of calcium in bath reduced the inhibitory effect of ethanol in contraction of bladder muscle strips.
CONCLUSIONS
This study shows that acute ethanol intoxication would reduce bladder muscle contractility and result in acute urinary retention.