Kinetics of dissolution of gaseous halothane in Krebs-Ringer's solution

The responses of biological tissues to volatile anaesthetics are commonly studied by incubating specimens in a bath containing dissolved anaesthetic. One accepted technique is to bubble an anaesthetic gas into several incubation chambers simultaneously. To assess the validity of this technique in producing dissolved anaesthetic (the biologically active form) at equal rates among the several chambers, we determined the kinetics of dissolution of halothane gas in three tissue incubation chambers containing Krebs-Ringer's solution. We found that (1) the dissolution kinetics were first-order in all three chambers; (2) the rate of halothane dissolution depended on the gas bubbling rate; (3) even with the same bubbling rates, chamber shapes and chamber volumes, the dissolution rates for the three chambers were not equal, suggesting that dissolution rate depended on small differences in chamber geometry; (4) the dissolution rates could be made equal by adjusting chamber bubbling rates according to calculations involving the first-order rate equation; and (5) the maximum coefficient of variation of dissolved halothane concentration was 9% at 63% approach to equilibrium and 3% at equilibrium.