Figure 3.

Diffusion of digoxin and ouabain into the nerve cord of D. nerii. As the two cardenolides have different specific activities, dpm values are not directly comparable. Data are, therefore, presented as pmol cardenolide/nerve cord (instead of dpm per nerve cord) to allow for quantitative comparisons. Nerve cords were incubated in equal concentrations of ouabain and digoxin, respectively (0.7 µM). Each data point is the mean of three nerve cords per treatment (i.e. 12 caterpillars were used in total).