Derivation of theoretical equations of the CO2 dissociation curve and the carbamate fraction in the Haldane effect.

Mochizuki, Mayumi; Takiwaki, Hirotsugu; Kagawa, Tomoko; Tazawa, Hiroshi

doi:10.2170/jjphysiol.33.579

Cited by 16 publications

(7 citation statements)

References 14 publications

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“…The estimation was done by using the Henderson-Hasselbalch equation, as described by MocHIZUKI et al (1983b). The carbamate C02-content in Haldane effect, R, was given by Japanese Journal of Physiology …”

Section: Of Parameter Valuesmentioning

confidence: 99%

Numerical solution of partial differential equations describing the simultaneous O2 and CO2 diffusions in the red blood cell.

Mochizuki

Kagawa

1986

Jpn.J.Physiol

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To describe the overall gas exchange rates in red blood cells (RBC), a computer program for solving the diffusion equations for 02, C02, and HC03 -that accompany the chemical reactions of Bohr-and Haldane-effects was developed. Three diffusion equations were solved alternatively and repeatedly in an increment time of 2 ms. After solving the diffusion equations the Poz, 02 saturation (S02), P02, pH, and HCO3 content were corrected by using the Henderson-Hasselbalch equation, where the buffer value was newly derived from the C02 dissociation curve. In computing the Haldane effect, the buffer value was taken to be 44 mmol l(RBC) -1 pH~ -1, so that the change in intracellular dissolved C02 caused by the Soz change was fully compensated by the subsequent C02 diffusion. The oxygenation and deoxygenation rate factors of hemoglobin were assumed to be 2.09(1 • -S)2'02 and 0.3 s -• Torr 1, respectively. The Poz change due to the Bohr-shift was computed from Hill's equation, in which the K value was given by a function of the intracellular pH. When the parameter values thus far measured were used, the computed Bohr-and Haldane-effects coincided well with the experimental data, supporting the validity of the equations. The overall gas exchange profiles calculated in the pulmonary capillary model showed that the C02 equilibration time was significantly longer than the oxygenation time.Key words ; diffusion in red blood cell, Bohr effect, Haldane effect, overall gas exchange rate.Under physiological conditions in the pulmonary and peripheral capillaries, the 02 and C02 diffusions into and out of the red blood cells (RBC) are mutually influenced by the Bohr-and Haldane-effects. To estimate the overall gas exchange rate, the oxygenation and deoxygenation rates as well as the C02 and HC03 -diffusion rates in the RBC must be solved simultaneously. However, because of

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Section: Of Parameter Valuesmentioning

confidence: 99%

Numerical solution of partial differential equations describing the simultaneous O2 and CO2 diffusions in the red blood cell.

Mochizuki

Kagawa

1986

Jpn.J.Physiol

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“…

Abstract The theoretical equations for the C02 dissociation curve derived by MocHIZUKI et al (1983) have made it possible to estimate the C02 contents in blood at any Pco2 by putting the intra-and extracellular bicarbonate contents at a certain Pco2 into them. Moreover, according to their Haldane effect equation, the carbamate and bicarbonate contributions are evaluated, when the Haldane effect and its plasma component are known along the PCo2 range.

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confidence: 99%

“…The other parameter values to be derived from the equations are tabulated in Table 1A, together with the equations through which the determinations were carried out. MocHizuKI et al (1983) also derived the simultaneous equations for the Haldane effect. Using their equations, the carbamate and bicarbonate contributions to the Haldane effect are evaluated from the intra-and extracellular bicarbonate contents of the oxygenated bloods, the Haldane effect and its plasma component.…”

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Quantitative analyses of the CO2 dissociation curve of oxygenated blood and the Haldane effect in human blood.

et al. 1983

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The theoretical equations for the C02 dissociation curve derived by MocHIZUKI et al. (1983) have made it possible to estimate the C02 contents in blood at any Pco2 by putting the intra-and extracellular bicarbonate contents at a certain Pco2 into them. Moreover, according to their Haldane effect equation, the carbamate and bicarbonate contributions are evaluated, when the Haldane effect and its plasma component are known along the PCo2 range. In order to accomplish the above calculation the water shifts due to the Pc02 and 02 saturation changes were measured as the changes of hematocrit. The hematocrit of oxygenated blood was linearly correlated to pH with a factor of -0.037, and the difference in hematocrit between oxygenated and deoxygenated bloods was 0.004 in terms of fractional hematocrit. The blood and plasma C02 contents measured at four different Pco2's were compared with the ones calculated by use of the intra-and extracellular bicarbonate contents at 42 Torr Pco2. The measured and calculated C02 contents coincided fairly well with each other. Using intra-and extracellular bicarbonate contents in oxygenated blood together with the Haldane effect and its plasma component, the carbamate contribution was then calculated. The carbamate content was about 1.2 mmol/liter blood over a Pcp2 range of 20 to 100 Torr, and its ratio to the total Haldane effect decreased from 50 to 40 %, as PC0, was increased. The ratio of the bicarbonate shift to the total bicarbonate change due to the Haldane effect, ranging from 0.82 to 0.66, was significantly greater than that measured by changing PCO2.

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“…According to MOCHIZUKI et al (1983) (40) is evaluated by subtracting the physically dissolved C02 and carbamate from the intracellular C02 content which is obtained from Eqs. (7a) and (7b) by putting [Hb]=1.…”

Section: Resultsmentioning

confidence: 99%

Diffusion coefficients of CO2 molecule and bicarbonate ion in hemoglobin solution measured by fluorescence technique.

1983

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: The diffusion process of CO2 within a thin layer of hemoglobin (Hb) solution was followed by pH-sensitive fluorescence of 4-methylumbelliferone. In the presence of sufficient carbonic anhydrase in the layer, the pH change was accelerated and determined only by the diffusion. The diffusion rate was reduced as the Hb concentration was increased. The pH rise observed in the CO2 diffusion out of the layer was slower than the pH fall caused by inward diffusion. However, the outward diffusion rate was faster than the inward diffusion rate in contrast to the pH change. The diffusion coefficients of molecular CO2 and bicarbonate ion were separately determined from the simulated and experimental P02-time curves by utilizing the non-linearity of the CO2 dissociation curve. The simulated curve was obtained from a numerical solution of the differential equation for diffusion by using the measured CO2 dissociation curve. The diffusion coefficient of CO2 was assumed to decrease exponentially with increasing Hb concentration. The diffusion coefficient of HCO3-was found to be reduced hyperbolically as the Hb concentration was increased. The diffusion coefficients of CO2 and HCO3-of 100% hemolysate were 0.34 x 10-5 and 0.14 x 10-5 cm2/sec, respectively. For the purpose of elucidating the interaction between the 02 and CO2 diffusions into the red cell, the CO2 diffusion coefficient in hemoglobin (Hb) solution was measured as the first step. Recently, pH-sensitive fluorescence of 4-methylumbelliferone has been used by Lubbers and his associates (LUBBERS et a!., 1979;OPITz et al., 1978) for measuring the PC02 of an isolated guinea-pig heart. 4-Methylumbelliferone (4-MU) is one of the coumarin derivatives (7-hydroxy-4-methylcoumarin). In the present paper, 4-MU fluorescence was applied to the measurement of CO2 diffusion rate in a thin Hb solution layer. The wavelength of the maximum intensity of 4-MU fluorescence is about 450 mm, which is considerably

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Derivation of theoretical equations of the CO2 dissociation curve and the carbamate fraction in the Haldane effect.

Cited by 16 publications

References 14 publications

Numerical solution of partial differential equations describing the simultaneous O2 and CO2 diffusions in the red blood cell.

Numerical solution of partial differential equations describing the simultaneous O2 and CO2 diffusions in the red blood cell.

Quantitative analyses of the CO2 dissociation curve of oxygenated blood and the Haldane effect in human blood.

Diffusion coefficients of CO2 molecule and bicarbonate ion in hemoglobin solution measured by fluorescence technique.

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