| Abstract: | The effect of micropuncture of the renal papilla through an intact ureter on urinary concentrating 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 X 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 X hr), renal PGE2 excretion was reduced to 22.3 +/- 5.1 pg/min prior to micropuncture and it remained low at 8.9 +/- 1.8 pg/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 X 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. |
