PARTIAL SPLENECTOMY, TRANSPOSITION OF THE SPLEEN TO THE ABDOMINAL-WALL OR SPLENOHEPATOPLASTY IN PORTAL HYPERTENSIVE RATS - EFFECTS ON PORTAL VENOUS-PRESSURE AND HOMEOSTASIS - MICROSCOPIC APPEARANCE OF THE TRANSPOSED SPLEEN

Reduction of the splenic volume by partial resection and collateral de velopment after transposition are of potential value in the elective t reatment of esophageal varices, hypersplenism and ascites. A study was performed on young Wistar rats. A simple animal model of extrahepatic portal hypertension was used, narrowing the portal vein to an outer d iameter of one millimeter (PVS). One day, three weeks and seven weeks after this operation the portal venous pressure was elevated as compar ed with the sham-operated controls. The portal hypertension was statis tically significant at week three (1.31 +/- 0.04 vs. 0.72 +/- 0.18 kPa , p = 0.01). Portocaval pressure gradient after partial resection of t he spleen (SR) and intramuscular transposition (IMTrans) was compared with the pressure gradient after graded portal vein stenosis. Three we eks after intramuscular transposition portocaval pressure gradient was reduced (1.46 +/- 0.38 vs. 1.74 +/- 0.13 kPa, n.s.). This data suppor ts the hypothesis that the portal venous high-pressure compartment and the systemic venous low-pressure compartment are maintained after dev elopment of natural shunts to the systemic circulation. In the followi ng experiment different types of splenic transposition were tested and compared to each other and a normal control group or to rats with por tal vein stenosis (PVS), respectively. After PVS, the animals were reo perated, an SR was performed and the wound surface of the spleen was t ransposed into the left abdominal wall subcutaneously (SCTrans) or int ramuscularly (IMTrans) or to the left liver lobe (splenohepatoplasty, SHP), respectively. After three weeks the animals underwent measuremen ts of organ weights, collections of blood samples and the spleen was i nvestigated histologically. Blood cell counts were nearly normal but t otal serum protein, albumin and the colloid osmotic pressure were slig htly diminished or significantly reduced (COP in the groups PVS+SR+IMT rans or SCTrans, p<0.05) compared to the controls. Differences to the group with portal vein stenosis (PVS) were not significant. Serum prot ein electrophoresis after splenic transposition revealed an unobtrusiv e distribution pattern. Animals after SHP had the best increase in wei ght and high protein levels, but splenohepatic collateral development seemed sparse. Differences of plasma ammonium levels were statisticall y not significant, but some animals had elevated levels after transpos ition. Morphometry of routine-stained spleen specimens showed an intac t immunoarchitecture of the transposed spleens.