Figure 2.

The EC₅₀ of alphaxalone (Site 3) is shifted differently by the presence of 25% of the EC₅₀ of either 3α5βP (Site 3) or etomidate (Site 1). In (a), the loss of righting reflexes (LoRR) is plotted against the free concentration of alphaxalone in the aqueous phase surrounding the tadpoles. The fraction of animals experiencing LoRR is represented by the vertical placement of the circles, with the number of animals tested displayed within them (total n = 55). The quantal data was fit as described in Methods and the EC₅₀ is displayed in Table 1. (b): Alphaxalone concentration response curves (C.R.C.) are shown in the presence of 25% of either 3α5βP's or etomidate's EC₅₀. (c): The concentrations of mixtures of alphaxalone and 3α5βP that together produce an EC₅₀ response are plotted. The concentration of either alphaxalone or 3α5βP was varied while the concentration of the other anaesthetic was fixed. In these and succeeding figures, the thick black line represents the theoretical line for additivity where α = 1 (Equation 1; Tallarida, 2016). The error bars shown are the SDs of the EC₅₀s.