Fig. 6. Relationships between the duration of the exposure to –5°C and the equilibrium potentials of sodium (upper part) and potassium ions (lower part) across the fat body membrane in the adults of Pyrrhocoris apterus belonging to three different acclimation groups (LD, SD, SDA; see Fig. 1). Each data point represents a mean ± S.E.M. of 6 (LD) or 3 (SD, SDA) equilibrium potentials calculated using the data shown in Fig. 4. The probabilities that slopes of linear regressions deviate from zero were: Na⁺: LD, P=0.756; SD, P=0.684; SDA, P=0.584; K⁺: LD, P<0.001; SD, P=0.001; SDA, P=0.117.