The Effects of Partial Outlet Obstruction on Bladder Strip Sensitivity to Glucose Deprivation: An In-Vitro Study in the Rat

Park, Jin Ik; Kwon, Heon Young

Abstract

The specific aim of the current study was to correlate the effects of partial outlet obstruction on the contractile responses of isolated strips of bladder smooth muscle to repetitive stimulation in the presence and absence of glucose. Adult male Sprague Dawley rats were subjected to partial outlet obstruction by the surgical placement of silk ligatures around the urethra. After two weeks, each rat was anesthetized and the bladder excised and isolated strip studies performed. After equilibration the strips were subjected to repetitive stimulations with FS, bethanechol, or KCI in the presence or absence of glucose. Both phasic and contractile responses were measured. The results are follows: 1. The maximal phasic response to FS was significantly decreased in the obstructed strips when compared to controls; no differences were noted for responses to bethanechol or KCI. 2. The tonic responses to all forms of stimulation were significantly decreased after obstruction; the tonic response to FS was decreased to a greater degree than were the tonic responses to bethanechol and KC1. 3. In the presence of glucose, the magnitude of phasic and tonic responses to bethanechol and KCl were well maintained in control strips during repetitive stimulation. 4. However, the phasic responses to FS were well maintained during repetitive stimulation whereas the tonic responses progressively decreased by approximately 60%. 5. In the absence of glucose, the tonic responses of control strips to all forms of stimulation were reduced to a greater degree than the phasic responses. 6. Partial outlet obstruction significantly reduced the phasic responses to FS, bethanechol, and KCI by 28.5%, 28.8% and 37.4% respectively and tonic response to FS was reduced to 28.6% of control value in glucose containing Tyrodes solution. Clinically significant reduction of bladder contraction is related to the reduction of glucose metabolism in obstructed bladder. Considering significant reduction of tonic response to FS, we think that neurotransmitter is major factor in contraction reduction in obstructed bladder.