Chloride current activated by cyclic AMP and parathyroid hormone in rat osteoblasts.
In primary cultures of rat osteoblasts, studied with the whole-cell configuration of the patch-clamp technique, 8-bromo-cyclic AMP (8BrcAMP) forskolin (FS) and 1-34 parathyroid hormone (PTH) were shown to activate a Cl conductance. This conductance shows a pronounced outward rectification, even with symmetrical Cl concentrations. It is blocked partially and reversibly by 4,4'-diisothiocyanatostilbene 2,2'-disulfonic acid (DIDS) or diphenylcarboxylate (DPC). The blockade induced by DIDS is time- and voltage-dependent. The Cl responses to FS and PTH develop slowly, after a delay of several seconds and are very slowly reversible. These responses were observed only in a fraction of the cells tested and their detection was favoured by cell dialysis. This Cl current should be taken into account for studying possible modulations of the voltage-gated Ca currents of osteoblasts. It is suggested that its physiological role may be related to the well-known morphological changes induced by PTH in osteoblasts. The cyclic AMP-sensitivity, the outward rectification and the sensitivity to dialysis of this Cl current are reminiscent of the properties of the cystic fibrosis-sensitive Cl channels of epithelial cells.
Chesnoy-Marchais
D
D
Laboratoire de Neurobiologie, Ecole Normale Supérieure, Paris, France.
Fritsch
J
J
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001565:Benzoates; D001713:Biphenyl Compounds / Q000494:pharmacology; D002264:Carboxylic Acids / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels; D002712:Chlorides / Q000502:physiology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D003956:Dialysis; D004553:Electric Conductivity; D008565:Membrane Proteins / Q000502:physiology*; D010006:Osteoblasts / Q000187:drug effects / Q000502:physiology*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D019379:Teriparatide
D001565:Benzoates; D001713:Biphenyl Compounds; D002264:Carboxylic Acids; D018118:Chloride Channels; D002712:Chlorides; D008565:Membrane Proteins; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D019379:Teriparatide; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C062963:diphenylcarboxylate; D000242:Cyclic AMP; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid