Plasma endotoxin concentration after an intraperitoneal injection of endotoxin in fed and fasted suckling rats

In the adult host response to endotoxin (lipopolysaccharide (LPS)) is dose-related. An intraperitoneal injection is commonly used for LPS administration in small animals. However, plasma endotoxin concentration following an intraperitoneal bolus injection of LPS is not well known. This study was performed to evaluate plasma endotoxin concentration following a bolus intraperitoneal injection of LPS in both fed and 24 h fasted 10 day old rats. Plasma endotoxin concentration increased in a dose-dependent manner after LPS injection (.03 or .1 mg/kg Salmonella enteritidis LPS) in both fed and fasted rats. Plasma endotoxin concentrations were higher (p < .05) in fed than fasted rats. A high dose of LPS (.1 mg/kg) induced 95 and 40% mortality in fed and fasted rats, respectively. A low dose of LPS (.03 mg/kg) induced 26.7% mortality in fed rats but no mortality in fasted rats. The hematocrit was significantly lower in fed than fasted rats. Plasma endotoxin inactivation was similar in fed and fasted rats. Host response appears to be related to plasma endotoxin concentration.