title: Pulmonary carbonic anhydrase in vertebrate gas exchange organs.
abstract: Carbonic anhydrase (CA) catalyzes the interconversion of CO(2) and HCO(3)(-). Intracellular (extravascular) and intravascular (extracellular) CA has been identified and localized in the lungs of reptiles and mammals. Less information is known, however, on the presence of intravascular CA in the lungs of amphibians and avians. In the present study, perfusion studies were used to compare the catalytic activity of pulmonary intravascular CA in reptiles and mammals. In addition, SDS-resistant CA activity was examined in microsomal fractions prepared from gill/lung tissue from representative animals in each vertebrate class. Finally, the CNO(-) sensitivity of the microsomal CA activity was compared. No SDS-resistant CA activity was found in gill microsomal fractions of several fish species. In contrast, the data suggest that SDS-resistant, intravascular pulmonary CA activity is present in air-breathing vertebrates with vastly differing lung morphologies and that the kinetics of inhibition is remarkably comparable between the vertebrate classes.
mesh_terms: D000818:Animals; D002256:Carbonic Anhydrases / Q000097:blood / Q000378:metabolism*; D002384:Catalysis; D005880:Gills / Q000201:enzymology*; D008168:Lung / Q000201:enzymology*; D011652:Pulmonary Circulation; D014714:Vertebrates / Q000378:metabolism*
chemical_list: D002256:Carbonic Anhydrases