Fig. 3. Davenport diagram with calculated P_CO2 isoclines showing changes in extracellular acid–base status of Boa constricta when fasting and during digestion. Numbers indicate time (h) after digestion. Untreated control snakes, solid circles; omeprazole-treated snakes, open circles. For comparison, acid–base values predicted in the case of no ventilatory compensation (i.e. maintained Pa_CO2) are shown in red, while the predicted acid–base status in case of a maintained pHa is shown in blue. The dotted line represents the non-bicarbonate buffer line obtained on Python molurus (Overgaard and Wang, 2002).