The effect of pretreatment with pentoxifylline on normothermic liver ischemia was studied in rats. This drug, a dimethylxanthine and fosfodiesterase inhibitor, improves microcirculation, decreases neutrophil activity in experimental sepsis and hemorrhagic shock, and inhibits "in vitro" cytokine production by isolated Kupffer cells. Partial liver ischemia was induced by occlusion of afferent vessels to the median and left lateral lobes for 60', followed by resection of nonischemic lobes just before reperfusion. The rats were divided in 4 groups: I (n = 6) sham operation, II (n = 6) resection of right and caudate lobes, III (n = 42) normal saline pretreatment and 60' ischemia, IV (n = 42) pentoxyfilline pretreatment (50mg/K/i.p. 2 h before clamping) and 60' ischemia. 12 animals were sacrificed 1 h and 6 h after reperfusion respectively (gr III and IV), and 20 rats were observed for a maximum of 24 h after reperfusion. Serum transaminases, LDH, CK (isoenzymes), bilirubin, and total bile acids were determined in each animal. A sample of the left lobe was taken for histological examination. Extent of necrosis 24 h after reperfusion was assessed. Bile output was measured before ischemia and during the first hour of reperfusion. Pentoxifylline pretreatment was associated with a lower rise in serum transaminases and LDH after reperfusion, but it did not modify the changes in either serum CK activity (mainly CKBB), or total bile acid concentration. A reduction of bile output was not avoided by pentoxifylline pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS)