Carbon dioxide transport and carbonic anhydrase in blood and muscle

Carbon Dioxide Transport and Carbonic Anhydrase in Blood and Muscle. Physio l. Rev. SO: 681-715, 2000. -CO2 produced within skeletal muscle has to leav e-the body finally via ventilation by the lung. To get there, CO2 diffuses from the intracellular space into the convective transport medium blood wit h the two compartments, plasma and erythrocytes. Within the body, CO2 is tr ansported fin three different forms: physically dissolved, as HCO3- or as c arbamate. The relative contribution of these three forms to overall transpo rt is changing along this elimination pathway. Thus the kinetics of the int erchange have to be considered. Carbonic anhydrase accelerates the hydratio n/dehydration reaction between CO2, HCO3- and H+. In skeletal muscle, vario us isozymes of carbonic anhydrase are localized within erythocytes but are also bound to the capillary wall, thus accessible to plasma; bound to the s arcolemma, thus producing catalytic activity within the interstitial space; and associated with the sarcoplasmic reticulum. In: some fiber types, carb onic anhydrase is also present in:the sarcoplasm. In exercising skeletal mu scle, lactic acid contributes huge amounts of H+ and by these affects the r elative contribution of the three forms of CO2. With a theoretical model, t he complex interdependence of reactions and transport processes involved in CO2 exchange was analyzed.