Secretory apical Cl- channels in A6 cells: possible control by cell Ca2+ and cAMP

Autor(en): Atia, F
Zeiske, W
Van Driessche, W
Stichwörter: A6 cells; ACTIVATION; ARGININE-VASOPRESSIN; cAMP; capacitance; cell-Ca2+; CFTR; CHLORIDE CHANNEL; Cl- current; conductance; INTRACELLULAR CALCIUM; KIDNEY-CELLS; LINE; noise analysis; Physiology; PROTEIN-KINASE-C; RENAL EPITHELIAL-CELLS; TRANSMEMBRANE CONDUCTANCE REGULATOR; TRANSPORT
Erscheinungsdatum: 1999
Herausgeber: SPRINGER VERLAG
Journal: PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
Volumen: 438
Ausgabe: 3
Startseite: 344
Seitenende: 353
Zusammenfassung: 
Distal kidney cells (A6) from Xenopus laevis were cultured to confluency on porous supports. Tissues were mounted in Using-type chambers to measure short-circuit current (I-SC), transepithelial conductance and capacitance, and to analyse the fluctuation in I-SC. In the absence of apical NaCl, but with normal basolateral NaCl Ringer's solution, extracellular addition of ATP, oxytocin, a membrane-permeant cAMP derivative, and forskolin produced a transient increase of the electrical parameters. Noise analysis revealed a spontaneous Lorentzian component. All responses depend strictly on the presence of basolateral Cl- and are caused by the activation of an apical (CFTR type) Cl- permeability. Repetitive treatment with ATP (or oxytocin) resulted in refractoriness. ATP and oxytocin acted antagonistically, whereas cAMP and ATP had additive effects. Incubation with the vesicular Ca2+ pump inhibitor thapsigargin or application of the Ca2+ channel blocker nifedipine elicited finite but variable Cl- channel activity. After treatment with nifedipine or thapsigargin, the response to oxytocin was severely impaired. We speculate that not only cAMP but also cell Ca2+ plays a crucial role in the activation of CFTR in A6. Ca2+ may be multifunctional but the rise in capacitance (apical area) observed with all stimulants strongly suggests its involvement in, and contribution to, exocytosis in the process of the CFTR-mediated transcellular Cl- movements.
ISSN: 00316768
DOI: 10.1007/s004240050919

Show full item record

Page view(s)

3
Last Week
1
Last month
0
checked on Feb 26, 2024

Google ScholarTM

Check

Altmetric