Effects of Inosine on Response to In Vitro Hypoxia in Absence of Substrate on Bladder Dysfunction in Adult Rats

Objectives To investigate the effects of inosine on in vitro ischemia-reperfusion injury to urinary bladders in adult rats. Inosine has neuroprotective effects against cerebral and cardiac ischemia-reperfusion injury. Methods A total of 18 adult male rats were used. Each rat was anesthetized, and the bladder was excised, cut longitudinally into 3 equal strips, and mounted in individual baths. Six strips were run simultaneously. Inosine (37.3 mM) was added to the baths containing strips 2, 4, and 6. All strips were equilibrated for 1 hour in oxygenated Tyrode solution containing glucose and at the end of the hour were stimulated with field stimulation, carbachol, and KCl. Strips 1 and 2 were subjected to repetitive stimulation (RS) by field stimulation (32 Hz) every 5 minutes for 1 hour; strips 3 and 4 were subjected to Tyrode equilibrated solution with nitrogen and no glucose for 1 hour; and strips 5 and 6 were subjected to in vitro hypoxia in the absence of substrate plus RS for 1 hour. All strips were then incubated in oxygenated Tyrode solution for 1 hour and stimulated as before. Results In normoxia, inosine had no beneficial effects either before or after RS. However, in the ischemic model, the bladder strips incubated with inosine showed significantly better contractile responses to stimulation with carbachol and KCl. After hypoxia without substrate plus RS, the strips incubated with inosine showed increased responses to all 3 forms of stimulation. Conclusions Inosine protected the contractile responses of the bladder strips after in vitro hypoxia without substrate with or without RS.