The experimental analysis of purinergic effects of copper and endogeneous thiols on neonatal and adult rat bladder

In the present study, we investigated the purinergic effects of copper and endogenous thiols on whole bladder isolated from neonatal or adult rat. In the experiments, L-cysteine, a thiol substance, enhanced the spontaneous contractions on isolated neonatal rat whole bladder while it had no effect on the spontaneous contractions of isolated adult rat whole bladder. Neocuproine (NC), a copper (I) chelator, also enhanced the spontaneous contractions on neonatal rat whole bladder but it caused only tonic contraction on adult rat bladder.1 µM nifedipine, 200 µM diamid, 50µM ATP, or 30µM NS1619, significantly reduced the amplitude and AUC of that spontaneous contractions enhanced by 1 mM L- cysteine or 50µM NC in isolated whole bladder from neonatal rat. Those substances reversed the decreament of frequency induced by L- cysteine or NC. Suramin, 100 or 200 µM, a P2X receptor antagonist, dose-dependently reduced the amplitude and AUC parameters of the spontaneous contractions increased by 1 mM L- cysteine or 50 µM NC on whole bladder preparation from newborn rat. But suramine had no effect on the frequency of the spontaneous contractions reduced in the presence of L- cysteine. On the other hand, 100 µM L-NA had no effect on the amplitude, AUC and frequency parameters of the spontoneous contractions increased by L-cysteine ( 1mM) or 50 µM NC.200 µM diamide, caused the tonic contraction of adult whole bladder. This contractile effect was significantly reduced by L-cysteine. 1 µM nifedipine, 50µM ATP, 100 µM suramin or 30µM NS1619, significantly reduced the contraction induced by NC. Meanwhile, 100µM L-NA did not affect the tonic contraction.These results showed that, purinergic patways, Ca2+- actived K+ channels, may play role on spontaneous contractions increased by L-cysteine in neonatal rat bladder tissues and thiols may play important role on bladder function. Also purinergic pathway may contribute to phasic or tonic activity of neonatal and adult rat bladder respectively.Key Words: ATP, Copper, Urinary bladder, purinergic system