title: Alpha-2 adrenergic receptors stimulate actin organization in developing fetal rat cardiac myocytes.
abstract: Expression of alpha(2)-adrenergic receptors (alpha(2)-AR) is very high in fetal rat heart although numbers decline with increasing gestational age. The current experiments were designed to identify the subtypes of alpha(2)-AR expressed and the function of these receptors in fetal cardiac myocytes. Expression of alpha(2)A and alpha(2)C, but not alpha(2)B, was confirmed in the myocyte population by indirect immunofluorescence microscopy with subtype-specific antibodies and by Western blot. Both dexmedetomidine, an alpha(2)-selective agonist, and norepinephrine, increased actin cytoskeleton organization and this increase was blocked by the alpha(2)-selective antagonist, atipamezole. Furthermore, dexmedetomidine inhibited isoproterenol-stimulated cAMP accumulation in isolated fetal rat heart and this was blocked by rauwolscine. Therefore, functional alpha(2)A and alpha(2)B subtypes are present in the fetal rat heart where they may have a role in cardiac development.
authors.affiliation: Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721, USA. porter_amy_c@lilly.com
authors.forename: Amy C
authors.initials: AC
authors.lastname: Porter
authors.forename: Samuel P S
authors.initials: SP
authors.lastname: Svensson
authors.forename: W Daniel
authors.initials: WD
authors.lastname: Stamer
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Bahl
authors.forename: Jeremy G
authors.initials: JG
authors.lastname: Richman
authors.forename: John W
authors.initials: JW
authors.lastname: Regan
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D006321:Heart / Q000196:embryology*; D008856:Microscopy, Fluorescence; D009206:Myocardium / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D010590:Phalloidine / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects*; D012235:Rhodamines; D015290:Second Messenger Systems / Q000187:drug effects
chemical_list: D000199:Actins; D005456:Fluorescent Dyes; D018341:Receptors, Adrenergic, alpha-2; D012235:Rhodamines; D010590:Phalloidine; D000242:Cyclic AMP