Cells of the carotid body express connexin43 which is up-regulated by cAMP.
We identified a gap junction protein subunit, connexin43 (Cx43) by immunofluorescence and immunoblotting, in cultured rat carotid body cells and in whole organs. In 1-week-old cultures, all cells were flat but after 3 h exposure to 8Br-cAMP (1 mM), tyrosine hydroxylase (TH) positive cells (chemoreceptors), but not TH negative cells, adopted a round body with multiple thin arborization processes. The incidence of dye coupling between cultured cells of the same type increased from 26% in controls to 73% after treatment with 8Br-cAMP. In control cultures, Cx43 immunoreactivity showed a diffuse perinuclear distribution and after 8Br-cAMP treatment, it was also found at cell-cell contacts. Both 8Br-cAMP-induced dye coupling and cellular redistribution of Cx43 were blocked by pretreatment with actinomycin D (5 microM), a mRNA transcription blocker. Moreover, 3 h exposure to 8Br-cAMP increased the levels of Cx43 in entire organs. We suggest that conditions that promote a sustained increase in cytosolic cAMP up-regulate coupling between carotid body cells in a transcription-dependent manner. The possible functional significance of these findings is discussed.
Abudara
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V
Departamento de Fisiología, Facultad de Medicina, Universidad de la República, General Flores 2125, CP 11800, Montevideo, Uruguay. abudara@fmed.edu.uy
Garcés
G
G
Sáez
J C
JC
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000818:Animals; D002344:Carotid Body / Q000166:cytology / Q000502:physiology*; D002450:Cell Communication; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics*; D000242:Cyclic AMP / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley
D018031:Connexin 43; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP