THE PHYSIOLOGICAL POSITION OF THE LIVER IN THE CIRCULATION IS NOT A MAJOR DETERMINANT OF ITS FUNCTIONAL-CAPACITY

The zonal patterns of gene expression in the liver of the rat are not affected by alteration of the afferent hepatic blood source. We invest igated whether afferent hepatic blood source or how rate affects the m etabolic capacity of the liver. Using microsurgical techniques, we cha nged the afferent hepatic blood source to solely arterial blood, solel y portal blood or solely caval blood. The transhepatic how rate was fo ur times higher in arterialized than in cavalized livers. Liver functi on was tested 2 wk, after surgery. Three liver functions were tested ( elimination of hepatic iminodiacetic acid from the liver and eliminati on of galactose and ammoniumbicarbonate from the circulation). Our res ults show that the afferent hepatic blood how rate rather than the sou rce of the afferent hepatic blood affects the elimination of the subst rates tested. We found that at the physiological how rate of approxima tely 15 ml/min and beyond, metabolic function does not depend on the f low of the afferent hepatic blood but that at lower how rates the how becomes a major determinant of the metabolic function of the Liver. We conclude that the position of the liver within the circulation (i.e. between the gastrointestinal tract and the systemic circulation) is ap parently not a prerequisite for adequate metabolic activity, at least for the substrates tested, provided that the liver is sufficiently per fused with blood.