Do barbiturates and their solutions suppress FMLP-induced neutrophil chemiluminescence?

The dose-response relationship of four commercially available barbiturates (methohexitone, pentobarbitone, phenobarbitone and thiopentone) and of their drug-free solutions on the production of oxygen radicals by neutrophils were tested by N-formylmethionyl-leucyl-phenylalanine (FMLP)-induced granulocyte chemiluminescence and in a cell-free chemiluminescence system. Methohexitone had no effect on neutrophil chemiluminescence. Pentobarbitone, phenobarbitone and thiopentone dose-dependently decreased FMLP-induced chemiluminescence and cell-free chemiluminescence. Suppression of neutrophil chemiluminescence by pentobarbitone and phenobarbitone was due to effects of the drug-free solutions and an osmolality greater than 360 mosmol kg-1. Only thiopentone suppressed granulocyte chemiluminescence drug-specifically. The physicochemical properties of commercially available barbiturate preparations and their solutions, as well as free radical scavenging capacity, have to be considered if these preparations are used to evaluate drug-specific effects on the production of oxygen radicals by neutrophils.