Atriopeptin III improves renal functions in a ureter-obstructed rat kidney model

The renal hemodynamic and excretory effects of atriopeptin III were studied in normal rat kidneys and in kidneys made dysfunctional by the application and release of a 24 h unilateral ureteral obstruction (UO24h), which decreased baseline glomerular filtration rate (GFR) by 80%. Atriopeptin III (0.5 nmol/kg i.v.) decreased blood pressure (10-15%) for more than 30 min, and increased urine flow rate and sodium excretion in normal and diseased kidneys for ca. 15 min. An initial enhancement of renal blood flow (ca. 20%) was apparent for less than 5 min. Atriopeptin III (bolus injection) temporarily enhanced the GFR 2-3-fold in the diseased (UO24h) kidneys, whereas no changes of GFR were noted in control kidneys. When atriopeptin III was continuously infused at a rate of 0.1 nmol/kg per min, GFR in UO24h kidneys increased from 0.28 +/- 0.08 ml/g per min to a stable level of 0.82 +/- 0.10 ml/g per min. Again, GFR in the control kidneys remained unaffected (1.25 +/- 0.08 ml/g per min). The enhancement of GFR in the UO24h kidney was associated with large increases of urine flow rate and sodium excretion.