Abstract
INTRODUCTION AND HYPOTHESIS: This study was conducted to investigate the urethral compensatory mechanisms to maintain urinary continence after pudendal nerve injury. METHODS: In naive, acute pudendal nerve transection (PNT) and 4 weeks after PNT (PNT-4w) female rats, leak point pressures (LPPs) during bladder compression were measured before and after the application of hexamethonium (C6), propranolol, and N (ω)-nitro-L: -arginine-methyl ester (L: -NAME), or terazosin and atropine. Responses to carbachol and phenylephrine of proximal and middle urethral muscle strips from naive and PNT-4w rats were also examined. RESULTS: LPPs were significantly decreased in PNT rats but not in PNT-4w rats. LPPs in PNT rats were significantly increased by C6 or L-NAME while LPPs in PNT-4w rats were significantly decreased by C6, or terazosin and atropine. Excitatory responses to carbachol and phenylephrine in the proximal urethral muscle were significantly larger in PNT-4w rats. CONCLUSIONS: These results suggest that α(1)-adrenoceptor and muscarinic receptor-mediated contractility is upregulated in the proximal urethra 4 weeks after PNT.