The rat urinaryprostacyclin as well as other

It has hitherto been assumed that urinary prostanoid excretion reflects renal and/or systemic prostanoid synthesis. Since the bladder forms an integral part of the urinary tract, we investigated whether this organ was capable of synthesising prostanoids. The rat urinary bladder was found to generate large amounts of 6-oxo-prostaglandin FjCC (the stable, spontaneous metabolite of prostacyclin) in vitro; it also produced smaller amounts of prostaglandin E2 and thromboxane B₂ (the stable, spontaneous metabolite of thromboxane A₂). Distension of the bladder and changes in pH and osmolarity of the incubate were found to markedly alter the production of these prostanoids. Urinary prostanoids may, therefore, reflect not merely renal and/or systemic prostanoid synthesis but also local synthesis and release by the bladder. The presence of these prostanoids in the bladder suggests that they may play a local role in cytoprotection and the regulation of bladder tone.