ABSTRACT
PURPOSE: The urinary bladder requires an adequate energy supply to maintain contractile function. The primary metabolic fuel is glucose. Through glycolysis and oxidative phosphorylation, high energy phosphate are generated, which in turn supply the metabolic energy for the contractile activities of the urinary bladder. The aim of this study was to determine the effects of glucose deprivation and recovery from glucose deprivation on the phasic and tonic components of the contractile responses of rabbit bladder strips to field stimulation, bethanechol, and KCl. MATERIALS AND METHODS: The urinary bladder bodies of mature male New Zealand White rabbits were separated from the base above the level of the ureteral orifices, and placed in Tyrode`s solution containing glucose in 37degrees C and equilibrated with 95% O2 and 5% CO2. Bethanechol(250microM) was left in contact with the strips for 4 minutes. KCI(120 mM) was left in contact with the strips for 4 minutes. Field stimulation(31Hz, 80V, 1ms) was maintained for 2 minutes. At the end of each incubation in glucose-free medium(100 minutes for FS, 180 minutes for KCl and bethanechol), the medium was changed to Tyrode`s solution containing glucose(1mg/ml) and stimulations continued for additional 90 minutes. Changes in muscle tension were measured and recorded on a Grass model 7D polygraph. RESULTS: The results can be summarized as follow : In response to glucose deprivation, (1) the tonic responses to field stimulation, bethanechol, and KCl all decreased at a significantly greater rate than the phasic responses; (2) the phasic and tonic responses to field stimulation were both reduced to less than 10% of control within 70 minutes of glucose deprivation; (3) the tonic response to bethanechol and KCl were reduced to approximately 10% of control within 180 minutes whereas the phasic responses remained stable at 40 and 30%, respectively; and (4) glucose replacement stimulated a rapid and nearly complete recovery of the phasic and tonic components of the response to field stimulation, bethanechol, and KCl. Concolusions: These results indicate that the tonic responses to all forms of stimulation are more sensitive to glucose deprivation than phasic responses.