| Abstract: | The effect of micropuncture of the renal papilla through an intact ureter on urinary concetrating ability of rats was examined. Micropuncture of the renal papilla caused a fall in urine osmolality in the punctured kidney from 1718 ± 106 to 1035 ± 79 mosmol/kg·H2O. In order to investigate the role of renal prostaglandins in this process, PGE2 excretion was measured and found to increase from 63.4 ± 14.0 to 205.5 ± 57.1 pg/min. Urine osmolality and PGE2 excretion from the contralateral kidney were not significantly altered. In animals given meclofenamate (2 mg/kg·hr), renal PGE2 excretion was reduced to 22.3 ± 5.1 pg/min prior to micropuncture and it remained low at 8.9 ± 1.8pg/min after papillary micropuncture. Meclofenamate also blocked the fall in urine osmolality caused by micropuncture of the renal papilla, with urine osmolality averaging 1940 ± 122 before and 1782 ± 96 mosmol/kg·H2O after the micropuncture. These results indicated that papillary micropuncture through an intact ureter increased renal PGE2 excretion and that a rise in renal production of PGE2 or some other prostanoid is associated with a fall in urine concentrating ability. |
