The potential therapeutic value of the chemically stable carbacyclin analogue iloprost on the course of postischemic acute renal failure was studied in six conscious chronically instrumented dogs and compared with five controls. Immediately after temporary ischemia (180-min cessation of blood flow by inflation of a pneumatic cuff), the investigational group PC received a continuous intraaortal infusion of iloprost (50 ng X min-1 X kg-1) over a period of seven days, whereas the control group C received 0.9% saline. The glomerular filtration rate [( 51Cr]EDTA clearance, endogenous creatinine clearance) was less decreased in the prostacyclin analogue group than in the control group [3rd day, 18 +/- 2.5 vs. 12 +/- 1 ml X min-1 (p less than 0.05); 7th day, 23 +/- 3 vs. 12 +/- 2 ml X min-1 (p less than 0.05)]. On day 1, renal blood flow (electromagnetic flow probe) was markedly lower in the control group (129 +/- 29 ml X min-1) than in the PC group (212 +/- 29 ml X min-1; p less than 0.05), even exceeding baseline levels in the latter group. Accordingly, the excessive rise in renal vascular resistance in the control group (+136%) was abolished in the PC group (-32%; p less than 0.01). Nitrogen retention was also markedly improved. Osmolar clearance was markedly lower in the control group (0.58 +/- 0.2 ml X min-1) than in the PC group (1.41 +/- 0.17 ml X min-1; p less than 0.05). It is suggested that the beneficial effect of iloprost is mediated by preservation of renal perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)