Effects of External Electric Fields Applied to Rat Liver In Situ on the Metabolism of Lipoproteins

Abstract

This study was undertaken to assess the effect of applying weak external electric fields (1.5 volts, 30–40 μA-DC) to rat liver in situ on the metabolism of ¹⁴C-FC-HDL or-LDL from donor rats. Twenty-nine male Wistar rats received either ¹⁴C-FC-HDL or ¹⁴C-FC-LDL intravenously in bolus. The field was applied beginning 150 min prior to injection, and was maintained for 255 and 240 min after injection of ¹⁴-LDL and ¹⁴C-HDL, respectively. For each injection, the animals were divided into bile+/blood-, bile-/blood+, and no-current groups. In both treatment groups secretion of ¹⁴C-bile salts mainly originating from ¹⁴C-HDL was delayed in comparison to controls. The delay was attributed to a disfunction of canalicular secretory membranes and/or inhibition of cholesterol 7 alpha-hydroxylase. With the field, ¹⁴C-LDL was taken up by the liver more slowly than in controls, probably as a result of a change in the environment of the LDL receptors. HDL and LDL are involved in the intrahepatic cholestasis process induced by the field and characterized by a decrease in bile salt secretion and, to a lesser extent, biliary cholesterol secretion.