Cellular actions of cAMP on HCO3(-)-secreting cells of rabbit CCD: dependence on in vivo acid-base status
| Autor: | C. Emmons, J. B. Stokes |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Male
medicine.medical_specialty Kidney Cortex Physiology Intracellular pH Renal cortex 4 4'-Diisothiocyanostilbene-2 2'-Disulfonic Acid Biology Reference Values In vivo Internal medicine Cyclic AMP medicine Animals Secretion Intercalated Cell Kidney Tubules Collecting Epithelial polarity Acid-Base Equilibrium Isoproterenol Hydrogen-Ion Concentration Molecular biology Adenosine In vitro Ion Exchange Bicarbonates medicine.anatomical_structure Endocrinology Female Rabbits medicine.drug |
| Zdroj: | American Journal of Physiology-Renal Physiology. 266:F528-F535 |
| ISSN: | 1522-1466 1931-857X |
| DOI: | 10.1152/ajprenal.1994.266.4.f528 |
| Popis: | HCO3- secretion by cortical collecting duct (CCD) occurs via beta-intercalated cells. In vitro CCD HCO3- secretion is modulated by both the in vivo acid-base status of the animal and by adenosine 3',5'-cyclic monophosphate (cAMP). To investigate the mechanism of cAMP-induced HCO3- secretion, we measured intracellular pH (pHi) of individual beta-intercalated cells of CCDs dissected from alkali-loaded rabbits perfused in vitro. beta-Intercalated cells were identified by demonstrating the presence of an apical anion exchanger (cell alkalinization in response to removal of lumen Cl-). After 180 min of perfusion to permit decrease of endogenous cAMP, acute addition of 0.1 mM 8-bromo-cAMP or 1 microM isoproterenol to the bath caused a transient cellular alkalinization (> 0.20 pH units). In the symmetrical absence of either Na+, HCO3-, or Cl-, cAMP produced no change in pHi. Basolateral dihydrogen 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM) for 15 min before cAMP addition also prevented this alkalinization. In contrast to the response of cells from alkali-loaded rabbits, addition of basolateral cAMP to CCDs dissected from normal rabbits resulted in an acidification of beta-intercalated cells (approximately 0.20 pH units). The present studies demonstrate the importance of the in vivo acid-base status of the animal in the regulation of CCD HCO3- secretion by beta-intercalated cells. The results identify the possible existence of a previously unrecognized Na(+)-dependent Cl-/HCO3- exchanger on the basolateral membrane of beta-intercalated cells in alkali-loaded rabbits. |
| Databáze: | OpenAIRE |
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