title: Testosterone induces an intracellular calcium increase by a nongenomic mechanism in cultured rat cardiac myocytes.
abstract: Androgens are associated with important effects on the heart, such as hypertrophy or apoptosis. These responses involve the intracellular androgen receptor. However, the mechanisms of how androgens activate several membrane signaling pathways are not fully elucidated. We have investigated the effect of testosterone on intracellular calcium in cultured rat cardiac myocytes. Using fluo3-AM and epifluorescence microscopy, we found that exposure to testosterone rapidly (1-7 min) led to an increase of intracellular Ca2+, an effect that persisted in the absence of external Ca2+. Immunocytochemical analysis showed that these effects occurred before translocation of the intracellular androgen receptor to the perinuclear zone. Pretreatment of the cells with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethylester and thapsigargin blocked this response, suggesting the involvement of internal Ca2+ stores. U-73122, an inhibitor of phospholipase C, and xestospongin C, an inhibitor of inositol 1,4,5-trisphosphate receptor, abolished the Ca2+ signal. The rise in intracellular Ca2+ was not inhibited by cyproterone, an antagonist of intracellular androgen receptor. Moreover, the cell impermeant testosterone-BSA complex also produced the Ca2+ signal, indicating its origin in the plasma membrane. This effect was observed in cultured neonatal and adult rat cardiac myocytes. Pertussis toxin and the adenoviral transduction of beta- adrenergic receptor kinase carboxy terminal peptide, a peptide inhibitor of betagamma-subunits of G protein, abolished the testosterone-induced Ca2+ release. In summary, this is the first study of rapid, nongenomic intracellular Ca2+ signaling of testosterone in cardiac myocytes. Using various inhibitors and testosterone-BSA complex, the mechanism for the rapid, testosterone-induced increase in intracellular Ca2+ is through activation of a plasma membrane receptor associated with a Pertussis toxin-sensitive G protein-phospholipase C/inositol 1,4,5-trisphosphate signaling pathway.
authors.affiliation: Centro FONDAP (Fondo de Invesigación Avanzada en Areas Prioritarias) Estudios Moleculares de la Celula, Universidad de Chile, Olivos 1007, Santiago 6640750, Chile.
authors.forename: Jose Miguel
authors.initials: JM
authors.lastname: Vicencio
authors.forename: Cristian
authors.initials: C
authors.lastname: Ibarra
authors.forename: Manuel
authors.initials: M
authors.lastname: Estrada
authors.forename: Mario
authors.initials: M
authors.lastname: Chiong
authors.forename: Dagoberto
authors.initials: D
authors.lastname: Soto
authors.forename: Valentina
authors.initials: V
authors.lastname: Parra
authors.forename: Guillermo
authors.initials: G
authors.lastname: Diaz-Araya
authors.forename: Enrique
authors.initials: E
authors.lastname: Jaimovich
authors.forename: Sergio
authors.initials: S
authors.lastname: Lavandero
mesh_terms: D000256:Adenoviridae / Q000378:metabolism; D000418:Albumins / Q000378:metabolism; D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000494:pharmacology; D005822:Genetic Vectors; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D015544:Inositol 1,4,5-Trisphosphate / Q000737:chemistry; D008856:Microscopy, Fluorescence; D015233:Models, Statistical; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D037342:Pertussis Toxin / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction; D013739:Testosterone / Q000378:metabolism / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D014966:Xanthenes / Q000494:pharmacology
chemical_list: D000418:Albumins; D000814:Aniline Compounds; D004963:Estrenes; D005456:Fluorescent Dyes; D010455:Peptides; D011760:Pyrrolidinones; D014966:Xanthenes; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C059715:Fluo-3; D013739:Testosterone; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D002118:Calcium