Effect of Glucagon on Plasma Glucose, Free Fatty Acids, α-Amino Nitrogen, Non Protein Nitrogen and Total Protein Concentrations and Hematocrit Values in Fed and Fasted Adult Female Chickens

Abstract

The effect of glucagon (0.2mg/kg BW) i.v., on plasma glucose, free fatty acids (FFA), α-amino nitrogen, non protein nitrogen (NPN) and total protein concentrations and hematocrit (Hct) values was investigated in fed and 4, 24 and 48hr fasted adult female white Leghorn chickens. Parameters described above were measured on nine successive blood samples collected at appropriately spaced time intervals over a 10hr period after the injection.During a 48hr fast, plasms FFA concentration rose rapidly for the first 4hr of the fast and reached a significantly higher peak at 24hr before declining slightly up to 48hr, while α-amino nitrogen and NPN levels fell significantly at 4 and 24hr and returned to the initial levels at 48hr. Whereas plasma total protein concentrations fell after 24hr, Hct values were elevated at 48hr, but there was no change in plasma glucose concentration.Glucagon injection significantly elevated both plasma glucose and FFA concentrations and significantly depressed both plasma α-amino nitrogen and NPN concentrations, indicating that this hormone stimulates lipolysis and enhances utilization of these nitrogen fractions by body tissues during the experimental period. However, the glucagon produced maximum concentrations and their persistencies in plasma glucose and FFA were differently modified by the lengths of fasting. Saline injection in control groups also caused a significant depression in plasma α-amino nitrogen concentration and decreased slightly the plasma NPN concentrations of chickens fed and fasted for 48hr. Glucagon caused a highly significant dramatic drop in plasma total protein level in 10min following the injection, suggesting that the hormone might rapidly spare the circulating plasma protein directly into probable tissue depot pools, or trigger an immediate metabolic breakdown of the protein. Hct values of successive blood samples were gradually lowered possibly due to hemodilution caused by extravascular fluid after repeated withdrawal of blood.