Change in PCO2 in red cell suspension following bicarbonate shift.

Shimouchi, Akito; Mochizuki, Mayumi; Niizeki, Kyuichi

doi:10.2170/jjphysiol.34.1015

Cited by 5 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, we determined j3 solely from the CO2 contents in a P~o2 range of 20 to 100 Torr. The ~~ value used was 62 mmol • l(RBC) 1 • pH -1 at a pH~ of 7.17 or a pH p of 7.4, which was compatible with the previous data (SIGGAARD -ANDERSEN, 1971;TAKIWAKI et al, 1983;SHIMOUCHI et al, 1984).…”

Section: Discussionsupporting

confidence: 87%

“…In the RBC, the C02 hydration or dehydration reaction occurs with the change in Pco2 and HC03 -values, as shown by NIIZEKI et al (1983NIIZEKI et al ( , 1984. Assuming that the carbonic anhydrase activity in the RBC is so high that the above reaction is completed in 1 ms, the changes in intracellular Pco2 and HC03 -are calculated by using the following equation (SHIMOUCHI et al, 1984;KAGAWA and MOCHIZUKI, 1984): The intracellular Pco2 and HC03 -changes that take place are also due to the change in Sot, i.e., the Haldane effect. When the deoxygenation reaction proceeds in the closed RBC, the HC03 -and carbamate concentrations increase, decreasing the Pco 2 thereof.…”

Section: Formulas For Correcting Intra-and Extracellular Pcoz and Hcomentioning

confidence: 99%

See 1 more Smart Citation

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

Mochizuki

Kagawa

1986

Jpn.J.Physiol

Self Cite

View full text Add to dashboard Cite

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

show abstract

Section: Discussionsupporting

confidence: 87%

Section: Formulas For Correcting Intra-and Extracellular Pcoz and Hcomentioning

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, because the modified Henderson-Hasselbalch equation (Eq. (17) of the preceding paper; SHIMOUCHI et al, 1984) used for correcting intracellular Pco2 and HC03-content includes two logarithmic terms, we first obtained the solution of an ordinary C02 diffusion with no chemical reaction terms. Then, the Pco2 change due to the hydration (or dehydration) reaction was calculated by using the modified Henderson-Hasselbalch equation, and the Pco2 and HC03~ content were corrected for each increment time and each volume element.…”

Section: Derivation Of Numerical Solutionmentioning

confidence: 99%

“…The i2(C02) thereof was obtained from the extracellular Pc02 change during the inward C02 diffusion and outward HC03-shift, and was used for determining the inward ~(HC03-). The buffer value of the RBC was cited from SHIMOucHI et al (1984). The C02 diffusions caused by the Pco2 and HC03-gradients across the RBC membrane were referred to as the primary and secondary diffusions, respectively.…”

Section: Derivation Of Numerical Solutionmentioning

confidence: 99%

“…NIIZEKI et al (1984) measured the rate of the HC03-shift in a closed RBC suspension and clarified that the intracellular HC03-change caused the P02 change, and subsequently a secondary C02 diffusion. Recently, SHIMOUCHI et al (1984) found that the intracellular Pco, change following the HC03-shift could be determined by using both the modified Henderson-Hasselbalch equation and the relation between the changes in buffer base and intracellular pH. They also suggested that the HC03-change following the C02 diffusion could be calculated by using a similar equation.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Numerical solution of partial differential equations for CO2 diffusion accompanying HCO3- shift in red blood cells.

Kagawa¹,

Mochizuki²

1984

Jpn.J.Physiol

Self Cite

View full text Add to dashboard Cite

A computer program for a numerical solution of the C02 diffusion in the red blood cell including the HC03-shift was developed. Comparing the calculated extracellular Pco 2 curve with the experimental data on the primary and secondary C02 diffusions, the permeabilities of C02 and HC03-across the red cell membrane, i2(C02) and i(HC03-), were determined as i2(C02)=2.5 x 10-6 cm/(sec . Torr), Inward i(HC03-) =5 x 10-4 cm/sec , Outward ~(HC03-)=7 x 10-4 cm/sec. The dependencies of the C02 diffusion rate on the hematocrit and initial intraand extracellular HC03-concentrations were examined using the above permeabilities. The half-time of the extracellular PC02 change in a closed RBC suspension was obviously reduced as the hematocrit and initial extracellular HC03-increased, while the effect of the initial intracellular HC03-was not significant. The C02 diffusion in vivo was simulated using pulmonary and tissue capillary models. The half-time of the extracellular HC03-change was about 0.15 sec, while that of the intracellular HC03-change ranged from 40 to 60 msec. Despite the considerable interest in the interaction of CO2 and 02 diffusions into and out of the red blood cells (RBC), the C02 diffusion process into the RBC has not been explained theoretically. Insofar as the two compartment model (HILL et al., 1973;FORSTER and CRANDALL, 1975) was used, the above interaction cannot be calculated. KERNOHAN et al. (1963) reported that the C02 hydration and dehydration reactions occur so fast in the RBC that the chemical equilibrium is established within 1 msec. Therefore, because the intracellular Pco2 change is mainly limited by the C02 and HC03-diffusions, we attempted to solve the differential equations for the diffusion numerically in a disc RBC model. In an effort to obtain a numerical solution, NIIZEKI et al. (1983) measured the diffusion rate of C02 in the RBC in a closed RBC suspension. In their experiment on the

show abstract

Secondary CO2 diffusion following HCO3- shift across the red blood cell membrane.

1984

View full text Add to dashboard Cite

In order to clarify the interaction between C02 diffusion and HC03-shift in the red blood cell (RBC), HC03-shift was measured by using a stopped flow method combined with fluorometry. When HC03-entered the RBC, the intracellular Pco2 increased, causing a secondary outflow of C02. Conversely, when HC03-ions flowed out of the RBC, the resulting decrease of PC02 caused an inward C02 diffusion. The Pco2 change caused by the inward HC03-shift was about 3-to 4-fold that of the outward shift. During the respective in-and outward-shifts, the mean half times of the extracellular pH changes were 0.15 and 0.13 sec. These were approximately twice as long as those of the primary C02 diffusion. The permeability of HC03-across the RBC membrane was obtained by comparing the experimental extracellular pH curve with a numerical solution for C02 and HC03-diffusions accompanied by the hydration and dehydration reactions. Thus the HC03-permeability was determined to be 5>< 10-4 and 7>< 10-4 cm/sec, in the in-and outward-HC03-shifts, respectively. The influence of Cl-concentration on HC03-permeability was tested by reducing the initial Cl-gradient across the RBC membrane. In a physiological Cl-concentration range the HC03-permeability was not affected by the Cl-gradient.Key Words:HC03-shift, C02 diffusion, HC03-permeability, stopped flow method, Cl-shift.In studies to elucidate the rate of gas exchange in vivo, the HC03-permeability across the red blood cell (RBC) membrane is an important parameters. KLOCKE (1976) measured the HC03-shift in RBC suspension by inhibiting the activity of carbonic anhydrase by using acetazolamide. However, because this enzyme is very active inside the RBC (KERNOHAN et a!., 1963), the rate of HC03-shift in the normal RBC seemed not to obey the rate measured in the suspension containing acetazolamide. Thus, we attempted to measure the rate of HC03-shift through extracellular pH by adding carbonic anhydrase into the normal RBC suspension. During the course of the pH measurement using a stopped flow apparatus, it was found that the intracellular HC03-change resulted in the Pco 2 change, causing a secondary C02 diffusion. Thus, from a recorded extracellular pH change which resulted from both the changes in Pco 2 and HC03 we attempted to determine HC03 -permeability. First, by varying the permeability a numerical solution for extracellular pH change was derived from the C02 diffusion equations accompanying the HC03-shift. Then, by comparing the computed pattern with the measured one, HC03-permeability was determined in terms of the transfer coefficient, rj-(HC03-). To obtain a numerical solution of the diffusion equation, estimated the diffusion coefficients for C02 and HC03r inside the RBC, and NnzEKI et al. (1983) measured the transfer coefficient for C02, 'j(C02) across the RBC membrane. SHIM0ucHI et al. (1984) clarified that the Pco2 change caused by the HC03 shift could be computed by a modified Henderson-Hasselbalch equation. Using these parameter values, KAGAWA and MocHlzuKi (1984) obtained...

show abstract

Change in PCO2 in red cell suspension following bicarbonate shift.

Cited by 5 publications

References 16 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.

Numerical solution of partial differential equations for CO2 diffusion accompanying HCO3- shift in red blood cells.

Secondary CO2 diffusion following HCO3- shift across the red blood cell membrane.

Contact Info

Product

Resources

About