EVALUATION OF THE REPERFUSION SYNDROME AFTER LIVER ISCHEMIA IN THE RAT

Hepatic surgery in man often requires a transient interruption of the blood flow to the liver. After the vascular declamping the hepatic rep erfusion induces a group of phenomena commonly called ''reperfusion in juries.'' The aim of this study was to evaluate the presence and effec t of vasoactive agents that could induce the acute pulmonary arterial hypertension which contributes to reperfusion injury, Wister rats were used. The hepatic ischemia was induced by cross-clamping the whole he patic hilus for 20, 40, and 60 min, In control experiments a sham oper ation was performed, Blood samples were collected from the suprahepati c inferior vena cave, Strips of the main pulmonary artery were set up in an isolated organ bath and tested for the response to noradrenaline , adrenaline, KCl, and plasma samples. Plasma levels of catecholamines were determined by high-performance liquid chromatography. Plasma con centration of noradrenaline significantly increased from 1.6 +/- 0.4 ( control) to 10.8 +/- 2.9 ng . ml(-1) and adrenaline concentration rose from 2.7 +/- 0.7 to 38.7 +/- 7.6 ng . ml(-1) after ischemia, Noradren aline potency, compared to control values, significantly increased aft er prolonged liver ischemia, The plasma samples collected after prolon ged liver ischemia caused a greater contraction of the pulmonary arter y than from control plasma. This contraction is partially inhibited by phentolamine, We conclude that hepatic ischemia modifies the response of the pulmonary artery to exogenous noradrenaline, At the same time it induces an increase in the plasma levels of adrenaline and noradren aline, The resulting combined effect may cause the pulmonary hypertens ion which has been observed in reperfusion injury. (C) 1996 Academic P ress, Inc.