抄録
[CO_2] and [HCO_3^-] obtained by varying Pco_2 in oxygenated or deoxygenated blood were designated by [CO_2]_p(ox) or [CO_2]_p(deox) and [HCO_3^-]p(ox) or [HCO_3^-]p(deox). The Haldane effects of [CO_2] and [HCO_3-] were obtained by subtracting [CO_2]_p(ox) from [CO_2]_p(deox) and [HCO_3^-]_p(ox) from [HCO_3^-]_p(deox). [CO_2] and [HCO_3^-] measured in blood at steady state in vivo have Pco_2-dependent respiratory components and Pco_2-independent metabolic components. The former components, designated by [CO_2]^* and [HCO_3^-]^*, depend on O_2 saturation and contain the Haldane effects. Thus, the venous-arterial differences for [CO_2]^* and [HCO_3^-]^*, designated by va[CO_2]^* and va[HCO_3^-]^*, have the Haldane effect components (va[CO_2]_HE and va[HCO_3^-]_HE) and the Pco_2-dependent components (va[CO_2]_p and va[HCO_3^-]_p). Here, we have attempted to derive the Haldane effects ([CO_2]_HE and [HCO_3^-]_HE) from the differences va[CO_2]^*－va[CO_2]_p and va[HCO_3^-]^*－va[HCO_3^-]_p. In the narrow venous-arterial Pco_2 range the ratios va[CO_2]_p/va[CO_2]^* and va[HCO_3^-]p/va[[HCO_3^-]^* are usually taken to be constant. Thus, values for forty five pairs of P_aco_2 and P_vco_2 were calculated from the equation for the ventilation/perfusion (V_A/Q_c) ratio using V_A/Q_c ratios ranging from 0.7 to 1.1 and values for P_aco_2 of 34 to 48 mmHg. From the ratios (va[CO_2]^*－va[CO_2]_p)/va[CO_2]^* and (va[HCO_3^-]^*－va[HCO_3^-]_p)/va[CO_2]^*, [CO_2]_HE and [HCO_3^-]_HE were obtained. The calculated values for [CO_2]_HE and [HCO_3^-]_HE agreed well with those measured in oxygenated and deoxygenated blood, demonstrating the validity of the equations for [CO_2]^* and [HCO_3^-]^*. Moreover, it was established that [CO_2]_HE and [HCO_3^-]_HE in vivo are proportonal to the respiratory quotient. difference in [CO2], Respiratory quotient Key words：CO_2 dissociation curve, Oxygen saturation, V_A/Q_c equation, Venous-arterial difference in [CO_2], Respiratory quotient
[CO2] and [HCO3-] obtained by varying Pco2 in oxygenated or deoxygenated blood were designated by [CO2]p(ox) or [CO2]p(deox) and [HCO3-]p(ox) or [HCO3-]p(deox). The Haldane effects of [CO2] and [HCO3-] were obtained by subtracting [CO2]p(ox) from [CO2]p(deox) and [HCO3-]p(ox) from [HCO3-]p(deox). [CO2] and [HCO3-] measured in blood at steady state in vivo have Pco2-dependent respiratory components and Pco2-independent metabolic components. The former components, designated by [CO2]* and [HCO3-]*, depend on O2 saturation and contain the Haldane effects. Thus, the venous-arterial differences for [CO2]* and [HCO3-]*, designated by va[CO2]* and va[HCO3-]*, have the Haldane effect components (va[CO2]HE and va[HCO3-]HE) and the Pco2-dependent components (va[CO2]p and va[HCO3-]p). Here, we have attempted to derive the Haldane effects ([CO2]HE and [HCO3-]HE) from the differences va[CO2]*-va[CO2]p and va[HCO3-]*-va[HCO3-]p. In the narrow venous-arterial Pco2 range the ratios va[CO2]p/va[CO2]* and va[HCO3-]p/va[HCO3-]* are usually taken to be constant. Thus, values for forty five pairs of Paco2 and PVco2 were calculated from the equation for the ventilation/perfusion (VA/QC) ratio using VA/QC ratios ranging from 0.7 to 1.1 and values for Paco2 of 34 to 48 mmHg. From the ratios (va[CO2]*-va[CO2]p)/va[CO2]* and (va[HCO3-]*-va[HCO3-]p)/va[CO2]*, [CO2]HE and [HCO3-]HE were obtained. The calculated values for [CO2]HE and [HCO3-]HE agreed well with those measured in oxygenated and deoxygenated blood, demonstrating the validity of the equations for [CO2]* and [HCO3-]*. Moreover, it was established that [CO2]HE and [HCO3-]HE in vivo are proportonal to the respiratory quotient.