metabolic effects of co 2 alice skoumalová. overview of oxidative fuel metabolism:
TRANSCRIPT
Metabolic effects ofCO2
Alice Skoumalová
Overview of oxidative fuel metabolism:
Carbon dioxide transport:
CO2 in the blood:
1. as HCO3- (ionization of H2CO3) 75-85 %
2. as carbamino groups (CO2 reacts with amino groups of proteins) 10-15 %
3. dissolved CO2 5-12 %
Partial pressures air-inspiration air-expiration arterial blood venous blood
pO2 (kPa) 21 15,3 12 – 13,3 4,6 - 6pCO2 (kPa) 0,03 4,4 4,6 – 6 5,3 – 6,6
CO2 + H2O H2CO3 H+ + HCO3-
erythrocytes (carbonate dehydratase)
O2 and CO2 transport:
Bohr effect (the increase in acidity of hemoglobin as it binds O2, releases H+)
Isohydric carriage of CO2 (Hb‘s ability to take up H+ with no change in pH through Bohr effect)
Chloride shift (the exchange of Cl- and HCO3- between the plasma and the erythrocyte)
Hypercapnia protects against free radical damage duringhypoxia-ischemia:
• Stabilization of the iron-transferrin complex• Shift of the oxygen-hemoglobin saturation curve to the right• Effects on metabolism (improve aerobic metabolism, reduced lactate
production, ATP generation)• Direct inhibition of the free radicals
Perinatal brain hypoxic-ischemic damageMechanical ventilationChronic respiratory failure
CO2: protective effect or radical damage ?