| First Author | Goldfarb DS | Year | 2000 |
| Journal | Am J Physiol Gastrointest Liver Physiol | Volume | 278 |
| Issue | 3 | Pages | G409-15 |
| PubMed ID | 10712260 | Mgi Jnum | J:60880 |
| Mgi Id | MGI:1354048 | Doi | 10.1152/ajpgi.2000.278.3.G409 |
| Citation | Goldfarb DS, et al. (2000) Acid-base effects on electrolyte transport in CA II-deficient mouse colon. Am J Physiol Gastrointest Liver Physiol 278(3):G409-15 |
| abstractText | To determine the role of carbonic anhydrase (CA) in colonic electrolyte transport, we studied Car-2(0) mice, mutants deficient in cytosolic CA II. Ion fluxes were measured under short-circuit conditions in an Ussing chamber. CA was analyzed by assay and Western blots. In Car-2(0) mouse colonic mucosa, total CA activity was reduced 80% and cytosolic CA I and membrane-bound CA IV activities were not increased. Western blots confirmed the absence of CA II in Car-2(0) mice. Normal mouse distal colon exhibited net Na(+) and Cl(-) absorption, a serosa-positive PD, and was specifically sensitive to pH. Decrease in pH stimulated active Na(+) and Cl(-) absorption whether it was caused by increasing solution PCO(2), reducing HCO(-)(3) concentration, or reducing pH in CO(2)/HCO(-)(3)-free HEPES-Ringer solution. Membrane-permeant methazolamide, but not impermeant benzolamide, at 0.1 mM prevented the effects of pH. Car-2(0) mice exhibited similar basal transport rates and responses to pH and CA inhibitors. We conclude that basal and pH-stimulated colonic electrolyte absorption in mice requires CA I. CA II and IV may have accessory roles. |
