Background: Bombesin (BOM) and gastrin releasing peptide (GRP) have been located to the lower urinary tract (LUT). However, there is a paucity of data demonstrating the impact of these endogenous peptides.
Objectives: The aim of the present study was to investigate the contractile actions of BOM and GRP on the female rat urethra in vitro and in vivo. Female Sprague-Dawley rats (n = 37) weighing approximately 225 g were used. Intraurethral pressure was recorded by a catheter placed at the maximum pressure zone corresponding to the intrinsic urethral sphincter.
Measurements: In vitro, changes in intraurethral pressure was conducted on perfused intact urethral/bladder preparations and are expressed as percentages of sphincteric intraurethral pressure achieved with noradrenaline. In vivo, changes in intraurethral pressure was conducted in anesthetized subjects and compared with the baseline intraurethral pressure and sham controls.
Results: In vitro, the increase in intraurethral pressure induced by BOM was 23.6 ± 3.2 cmH(2)O, exceeding the pressure evoked with NA by 9.6 cmH(2) O or 174.4% whereas GRP induced a maximum pressure of 10.7 ± 1.6 cmH(2) O, an increase of 2.2 ± 0.5 cmH(2) O or 82.9% (P < 0.05) of the NA evoked pressure. In vivo, the mean baseline pressure was 22.9 ± 1.4 cmH(2) O. The intraurethral pressure evoked by BOM was 50.6 ± 6.3 cmH(2) O (P < 0.05), and for GRP, the evoked intraurethral pressure was 56.2 ± 13.4 cmH(2) O (P < 0.05).
Conclusions: The present data suggest that both BOM and GRP may contribute to the control of continence by their contractile action on the sphincters of the LUT outflow region.
Copyright © 2011 Wiley-Liss, Inc.