RESUMO
Urodynamic and pharmacological studies were performed to investigate the effect of crystalluria on the micturition reflex and the involvement of glutamatergic transmission. The rats, which were given LP-805 (100 mg/kg/day) orally for 12 days, voided crystalluria. The pH of these crystalluria (LP-805 urine) was the same as normal urine. The amount of crystals was 70-100/division magnified 400 x. The end of the crystals was sharp. Intravesical administration of LP-805 urine induced hyperreflexia of the micturition reflex in normal rats. When the infusion solution was changed to LP-805 urine from saline, the latency was reduced to 57.6+/-2.1% of control in single cystometrogram (CMG) or was reduced to 51.4+/-0.9% of control in continuous CMG. The voiding volume was reduced to 52.1+/-3.6% of control in single CMG or was reduced to 62.5+/-0.8% of control in continuous CMG. These parameters were recovered after LP-805 urine was removed. Intravesical administration of acetic acid did not induce hyperreflexia of the micturition reflex in LP-805-treated rats. These data suggest that the chronic irritation by aculeate crystals might induce hyperreflexia of the micturition reflex, which increase afferent neuronal activity. Intravenous administration of MK-801 (0.001 to 1 mg/kg) inhibited the micturition reflex in a dose-dependent manner. The ID50 in LP-805-treated rats (0.03 mg/kg i.v.) was lower than that in normal rats (0.56 mg/kg i.v.). After chronic irritation of the bladder epithelium, MK-801 sensitivity was enhanced for the micturition reflex. These data suggested that crystalluria elicit hyperreflexia in the micturition reflex that mediated with NMDA glutamatergic receptors.
