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Oxygen-linked CO2 transport in sheep blood
The American Journal of Physiology
|August 1, 1975
Summary
Hemoglobin concentration influences oxygen-linked carbamate formation in sheep blood. Lower concentrations reduce the Bohr effect and oxygen affinity, impacting carbon dioxide transport.
Area of Science:
- Physiological Chemistry
- Respiratory Physiology
- Biochemistry
Background:
- Carbon dioxide (CO2) transport in blood involves complex interactions with hemoglobin.
- Oxygen-linked carbamate formation is a key mechanism for CO2 binding to hemoglobin.
- The influence of hemoglobin concentration on this process requires further elucidation.
Purpose of the Study:
- To investigate the effect of hemoglobin concentration on oxygen-linked carbamate formation in sheep hemoglobin B.
- To quantify the impact of CO2 on oxygen affinity and the Bohr effect across different hemoglobin concentrations.
- To determine the contribution of oxygen-linked CO2 to overall carbon dioxide exchange in sheep blood.
Main Methods:
- Analysis of CO2 effects on oxygen affinity and Bohr effect in red cell suspensions and dilute (1.3 mM Hb4) and concentrated (5 mM Hb4) hemoglobin solutions at 37°C.
- Measurement of CO2 binding curves for deoxygenated and oxygenated whole blood and hemoglobin solutions.
- Calculation of oxygen-linked carbamate fraction and its contribution to CO2 exchange, considering a respiratory quotient of 0.85.
Main Results:
- Lower hemoglobin concentrations (1.3 mM Hb4) significantly reduced the Bohr effect and oxygen affinity in the presence of CO2 compared to red cell suspensions or concentrated solutions (5 mM Hb4).
- The fraction of oxygen-linked carbamate was higher in dilute hemoglobin solutions (0.156 M HbCO2/M HbO2) than in concentrated solutions (0.12 M HbCO2/M HbO2) at pH 7.2.
- Total oxygen-linked CO2 in sheep whole blood was 0.18 M CO2/M O2, with 70% attributed to oxygen-linked carbamate, contributing 21% to CO2 exchange.
Conclusions:
- Hemoglobin concentration is a critical factor affecting oxygen-linked carbamate formation.
- Dilute hemoglobin solutions exhibit altered CO2-hemoglobin interactions compared to concentrated solutions or red blood cells.
- Oxygen-linked carbamate plays a significant role in sheep blood's carbon dioxide transport capacity.