Polymorphonuclear leukocytes (PMN) form a major part of the body's nonspecific first line of defense. An early event, prerequisite for the effective restriction of microbial invasions, is the chemotactic movement of activated neutrophils towards the invading organisms. To date, only limited and contradictory data exist regarding the effects of various intravenous anesthetic agents on neutrophil migration. In this study, the influence of ketamine, etomidate, midazolam, diazepam, and six commonly used i.v. barbiturates (hexo-, pheno-, pentobarbital, methohexital, thiopental, thiobutobarbital) on the in vitro motility of isolated human PMN was tested. Purified PMN (greater than 95%) were obtained from venous blood samples of healthy adults by dextran sedimentation, subsequent ammonium chloride treatment for red blood cell lysis, and Ficoll-Hypaque gradient centrifugation. Random and chemotactic migration were assessed under 1% agarose in the presence of 10(-3)-10(-7) M logarithmic dilutions of the agents in antibiotic free migration medium (MEM). N-fMet-Leu-Phe (FMLP) served as the standardized chemical attractant (10(-7) M). PMN motility was unaffected by ketamine and etomidate, but a significant (P less than 0.001), dose - related depression could be observed with both benzodiazepines at concentrations exceeding 10(-5) M (Fig. 1). Except at 10(-3) M concentration, this migratory inhibition proved to be easily reversible (Fig. 3). At the highest concentration tested (10(-3) M), all the barbiturates caused a significant (P less than 0.001) but completely reversible depression of random as well as chemotactic PMN migration (Table 1).(ABSTRACT TRUNCATED AT 250 WORDS)