Prostaglandin E2 release from isolated bladder strips in rats with spinal cord injury

Aim: Recent studies have shown that various factors contribute to the increased excitability into the bladder afferent nerves in spinal cord injury (SCI) rats. It has been reported that prostaglandins (PG) act as local modulators of reflex micturition in pathological conditions. In the present study, we measured the amount of PGE(2) release from the bladder of chronic SCI rats. Methods: Spinal cord was transected at the level of T8-9 in adult female Sprague-Dawley rats. After 10 weeks, specimens of the urinary bladder were obtained from SCI rats and sham-injured control rats, and bladder strips were dissected from the bladder. Using an muscle-bath technique and a microdialysis procedure, the dialysate, containing substance released from bladder strips, was collected. Then the amount of PGE(2) in the dialysate was measured by radioimmunoassay. Results: Excretion of urinary PGE(2) was significantly higher in SCI rats than in control rats. PGE(2) release from bladder strips was significantly higher in SCI rats than in control rats. Removal of urothelium caused significant decreases in PGE(2) release in both control and SCI rats. Stretches of the bladder strips caused significant resting tension-dependent increases in PGE(2) release from the strips with urothelium. Conclusions: The present data suggest that bladder urothelium partly contributes to the increase in PGE(2) release from the bladder, and that bladder distension may cause increases in PGE(2) release in SCI rats.