ISSN:
1432-1424
Keywords:
rat lactotrophs
;
calcium-activated chloride conductance
;
TRH stimulation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary We studied a chloride (Cl-) conductance activated by calcium (Ca2+) in normal rat lactotrophs and compared its activation during TRH stimulation in normal rat lactrotrophs and in GH3 tumoral lactosomatotrophs cells, using the whole-cell configuration of the patch-clamp technique. The Cl- specificity of the conductance was assessed by manipulation of internal and external Cl- concentrations. The reversal potentials were in agreement with those predicted by the Nernst equation. Ca2+ ionophore A23187 and membrane depolarizations activated the Cl- conductance. However, a feedback effect of Cl- gradient modifications on Ca2+ movements was also observed in normal lactotrophs. In the latter, TRH (100 nm) mobilization of intracellular Ca2+ activated this Cl- conductance together with the potassium (K+) conductance when both ions were present in the intracellular medium (IM) or alone when K+ was absent. Chloride conductance was not activated in the GH3 cells, where mobilization of intracellular Ca2+ by TRH (100 nm) activated only Ca2+-dependent K+ conductance. It seems likely that the activation of Cl- conductance in these two different cell types involves different mechanisms. This work was supported by grants from Centre National de la Recherche Scientifique (URA 1200), Université de Bordeaux 2, Etablissement Public Régional, and Fondation pour la Recherche Médicale.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00233459
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