Expression of alpha1-adrenergic receptor subtypes in heart cell culture.
Three alpha1-AR subtypes have been cloned so far and are designated as alpha1a, alpha1b,, and alpha1d. Organ-specific distribution pattern and subtype-specific effects are known but not fully understood. To address a cell-type specific expression pattern in the heart we investigated expression pattern of alpha1-AR subtypes on RNA- and protein-level in heart tissue, cultured cardiomyocytes and non-myocytes of the rat. Each alpha1AR-subtype mRNA was present in neonatal and adult rat heart culture but the relative distribution pattern was significantly different. While the alpha1a-AR subtype is preferentially expressed in adult cardiomyocytes, the alpha1b-AR subtype was preferentially expressed in the non-myocyte cell fraction. The RT-PCR results were confirmed by Western-blotting (alpha1b) and immunocytochemical studies. Incubation with an alpha1-agonist (phenylephrine) for 72 h led to a significant reduction of the alpha1b-AR in neonatal heart cell culture on both mRNA and protein level. In contrast, incubation with an alpha1-antagonist (prazosin) induced a 1.6 fold upregulation of the alpha1a-AR mRNA without significant effects on radioligand binding and functional assay. The results indicate a distribution pattern of the alpha1-AR subtype which is specific for cell type and ontogeny of the rat heart and may be regulated by adrenergic agents.
Luther
H P
HP
Medical Clinic I, Department of Cardiology, Humboldt-University (Charité), Berlin, Germany.
Podlowski
S
S
Schulze
W
W
Morwinski
R
R
Buchwalow
I
I
Baumann
G
G
Wallukat
G
G
D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D007150:Immunohistochemistry; D008297:Male; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D009928:Organ Specificity; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020033:Protein Isoforms; D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D011224:Prazosin