HEMODYNAMIC STUDY OF THE PORTAL VENOUS SYSTEM IN A MODEL OF WARM LIVER ISCHEMIA/REPERFUSION INJURY IN RATS

Abstract

Background: Liver transplantation and resections require temporary interruption of the hepatic blood flow resulting in ischemia/reperfusion (IR) injury. The hepatic microcirculatory impairment is related to the severity of the IR injury and may be reflected in the liver macro hemodynamic. There is aninverse correlation between hepatic blood flow and the postoperative transaminases. The aim of the study was to evaluate the hemodynamic of the portal venous system after warm liver IR injury. Methods: Eighteen Wistar rats were divided into 3 groups: I) Control; II) sham: rats submitted to resection of right and caudate liver lobes; III) Ischemia (IR): rats subjected to 60 min of partial warm liver ischemia of left and median lobes, followed by resection of non-ischemic lobes at reperfusion. Four hours after reperfusion rats were anesthetized and submitted to mechanical ventilation. Carotid artery was cannulated for mean arterial pressure (MAP). Mean portal venous flow (MPF) was assessed by a perivascular flowprobe. A micropressure probe was introduced into portal vein to assess the mean portal venous pressure (MPP). At the end blood was collected for AST and ALT analysis. Results: The mean weigh of rats was 229 ± 18 g. AST and ALT were increased in IR group (6.675 ± 1.687 and 5.793 ± 1.119 U/L) compared to sham (897 ± 303 and 815 ± 433 U/L) and control groups (99 ± 28 and 64 ± 27 U/L), P < 0.05. MAP was decreased in IR group (90 ± 17 mmHg) compared to control group (114 ± 9 mmHg), P < 0.05; but there is no difference when compared to sham group (106 ± 16 mmHg). MPP was increased in sham group (9.3 ± 1.8 mmHg) compared to control (6.2 ± 1.7 mmHg) and IR (4.5 ± 1.7 mmHg) groups, P< 0.05. MPF was decreased in IR group (5.0 ± 2.2 ml/min) compared to sham (12.3 ± 2.1 ml/min) and control (12.2 ± 1.9 ml/min) groups, P< 0.05. Conclusions: This study showed that four hours after warm liver ischemia/reperfusion, the total hepatic blood flow is reduced, demonstrated by the decrease of 60% in mean portal flow and 21% in mean arterial pressure. These changes in the hepatic hemodynamics may be correlated with the severity of the liver ischemia/reperfusion injury. This model can be a tool to evaluate protective strategies against liver IR that impact hepatic macro hemodynamics.