Theophylline prevents the hypoxemia-induced renal hemodynamic changes in rabbits.

The acute renal effects of hypoxemia and the ability of theophylline to prevent these effects were assessed in anesthetized and mechanically-ventilated newborn and adult rabbits. Renal blood flow (RBF) and glomerular filtration rate (GFR) were determined by the clearance of para-aminohippuric acid and inulin, respectively. Each animal acted as his own control. In 14 newborn rabbits (group 1), hypoxemia was significantly associated with a fall in GFR (-22 +/- 6%) and filtration fraction (-17 +/- 3%) and with an increase in renal vascular resistance (+13 +/- 6%). Hypoxemia also induced a significant decline in GFR (-27 +/- 6%) and RBF (-29 +/- 6%) in 7 adult rabbits (group 3). Intravenous theophylline (0.5 mg/kg) completely prevented the hypoxemia-induced changes in GFR, filtration fraction (FF) and renal vascular resistance (RVR) in 8 newborn rabbits (group 2). An intravenous dose of 2.4 mg theophylline given after the induction of hypoxemia partially reversed the drop in GFR in adult rabbits (group 3). Separate renal functions were studied in 8 additional adult rabbits (group 4). Low-dose theophylline (27 micrograms/min) infused intra-arterially in the left kidney partially prevented the hypoxemia-induced decline in urine flow rate, GFR, RBF, FF as well as the increase in renal vascular resistance. The beneficial effects of theophylline could be mediated by its adenosine antagonistic properties.