Influence of temperature on the CO2 dissociation curve of the turtle Pseudemys scripta

Carbon dioxide dissociation curves were constructed for blood of Pseudemys scripta. These were shifted by temperature and CCO2 was inverse to temperature at common PCO2. CO2 capacitance coefficients for oxygenated and deoxygenated blood (beta oxy, beta deoxy) were inverse to temperature at reported in vivo arterial PCO2's as was the Haldane effect. Data for in vivo PCO2 and Hb saturation of pulmonary arterial and venous blood allowed determination of effective beta which closely reflected values of beta oxy and beta deoxy at different temperatures. This indicates an influence of curve shape on beta eff at in vivo PCO2's. A high degree of correlation was found between air convection requirement (liters of gas ventilated per mmol CO2 produced) and beta eff at different temperatures. The inverse relationship between beta eff and temperature strongly influenced perfusive conductance of CO2 (Gperf = Vb X beta) and contributes to the temperature-independent stability of ventilatory to perfusive conductance ratio and the CO2 content of the animal. The influence of variable curve shape and Haldane effects must be considered as determinants of beta eff in the quantitative assessment of CO2 transport in this species.