The rise of the plasma lipid concentration elicited by dietary sodium chloride restriction in Wistar rats is due to an impairment of the plasma triacylglycerol removal rate

Studies in humans have indicated that dietary salt restriction raises plasm a levels of total cholesterol (TC) and triacylglycerols (TAG). In order to explain the mechanisms involved, a rat experimental model was developed con sisting of chronic feeding ad libitum isocaloric diets with variable sodium chloride contents. Rates of synthesis of plasma TAG were measured either a s the increase of plasma TAG after blocking its removal from plasma by the intra-arterial pulse infusion of Triton-WR 1339, or as the plasma rate of i ncorporation of [C-14]-oleic acid [C-14]-TAG. Plasma TAG removal rate was d etermined by the intra-arterial pulse infusion of a lipid emulsion. Severe salt restriction increased the plasma concentrations of TAG (71%) and of TC (10%). This result was not due to modification of the rate of synthesis of plasma TAG but was attributed to a 55% slower rate of removal of the TAG-c ontaining lipoproteins. An increased plasma non-esterified fatty acid conce ntration, probably due to a salt restriction-related insulin resistance, ma y have impaired the activity of the enzyme lipoprotein lipase. (C) 2001 Els evier Science Ireland Ltd. All rights reserved.