Effect of meal components on peripheral and portal plasma glutamate levels in young pigs administered large doses of monosodium-L-glutamate

Abstract

Mean peak plasma glutamate concentrations and area under the plasma glutamate concentration-time curve are much lower in adult humans ingesting monosodium L-glutamate (MSG) in formula than in water. The present study investigated the effects of individual meal components on portal and vena caval plasma glutamate concentration in young pigs administered MSG. Portal vein catheters and gastrojejunal tubes were placed in four young male pigs, and the animals were allowed to recover. Each animal was then administered four water solutions providing 500 mg/kg body weight MSG in a Latin square design. One solution provided only MSG; the second provided MSG and 1 g/kg body weight metabolizable carbohydrate (partially hydrolyzed corn starch); the third provided MSG and 1 g/kg body weight nonmetabolizable carbohydrate (beta-cellobiose); and the fourth provided MSG and 0.4 g/kg body weight of an amino acid mixture (Aminosyn, Abbott Laboratories, North Chicago, Ill). Mean peak plasma glutamate concentration and area under the plasma glutamate concentration-time curve were significantly lower (P less than 0.05) in both portal and vena caval blood when MSG was administered with metabolizable carbohydrate than when administered in water. Simultaneous ingestion of MSG with nonmetabolizable carbohydrate (beta-cellobiose) or amino acids had no significant effect on either mean peak portal or vena caval plasma glutamate concentration or area under the plasma glutamate concentration-time curves when compared to values observed when MSG was administered alone. The data suggest that metabolizable carbohydrate is the meal component affecting plasma glutamate concentration.