Researchers Assess Effects of Ketamine on Endotoxin-induced Shock in Rats. Taniguchi et al. (page 928)

Taniguchi et al.  randomly assigned 40 rats to one of five groups of eight rats each:Escherichia coli  endotoxin alone; saline only (control); ketamine (10 mg · kg−1· h−1) only; pretreatment with ketamine before endotoxin administration; or posttreatment with ketamine 2 h after endotoxin administration. For a 5-h period after endotoxin injection, the team measured hemodynamic parameters, acid–base status, and plasma concentrations of the cytokines tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) in all rats.

Systolic arterial pressure, arterial p  H, and bicarbonate concentration all decreased in animals that received endotoxin alone or posttreatment with ketamine after endotoxin injection. Five hours after endotoxin injection, a significantly lower arterial p  H was observed in the endotoxin-alone group. Acid–base balance was better maintained in groups to which ketamine was administered. Endotoxin injection increased the TNF-α concentration in the endotoxin-alone, pretreatment, and posttreatment groups, but the concentration remained significantly less in the pretreatment group than in the other two groups at 2 h after injection. Ketamine administration inhibited the development of hypotension, metabolic acidosis, and cytokine response in endotoxin-exposed rats. Although further investigation is necessary to determine the mechanisms responsible for these inhibitory effects of ketamine, its use as an anesthetic agent may offer advantages in endotoxemia.