MICROVASCULAR CHANGES IN LIVER AFTER ISCHEMIA-REPERFUSION INJURY - PROTECTION WITH MISOPROSTOL

Morphological changes in the hepatic microvasculature were studied in experimentally induced ischemia-reperfusion injury in the rat using a vascular casting technique. Partial hepatic ischemia was induced for 9 0 min followed by 24 hr of reperfusion. Microvascular casting was perf ormed after 24 hr reperfusion by either intraarterial or intravenous i nfusion of acrylic resin (Mercer). After corrosion of the tissue, the cast was examined by scanning electron microscopy. Casts of normal liv ers showed good patency with no evidence of unfilled areas. The mean d iameter of sinusoids was 14 +/- 3 mu m with those in zone 1 slightly s maller than those in zone 3. Liver casts from rats subjected to ischem ia and reperfusion resulted in gross disruption of normal architecture . The common characteristics seen in both prograde and retrograde cast s were clusters of closed sinusoids around zones 2 and 3 of the liver acini, which resulted in cavities of various sizes. Varicosities were observed in some areas. The mean diameter of sinusoids in areas of pat ent microvascular structure (10 +/- 2 mu m) was significantly smaller compared to those in normal livers (P < 0.001). Misoprostol given at 1 min before reperfusion markedly reduced the microvascular injury. The hepatic microvasculature was generally intact with mild focal unfille d areas. The majority of the sinusoids were of normal size and no clus ters of blind ending sinusoids were detected. The present study shows that hepatic ischemia-reperfusion results in extensive microvascular i njury in the liver. The protective effects of misoprostol against this injury may occur at the vascular level.