title: Novel mitogenic effect of adenosine on coronary artery smooth muscle cells: role for the A1 adenosine receptor.
abstract: Adenosine is a vascular endothelial cell mitogen, but anti-mitogenic for aortic smooth muscle cells and fibroblasts when acting via the A2B adenosine receptor. However, we show that adenosine increases porcine coronary artery smooth muscle cell (CASMC) number, cellular DNA content, protein synthesis, and PCNA staining. RT-PCR analysis indicates that porcine CASMC express A1, A2A, A3, and barely detectable levels of A2B receptor mRNAs. The mitogenic effect of adenosine is mimicked by NECA, CCPA, and R-PIA, but not by CGS21680and 2-Cl-IB-MECA, and is inhibited by DPCPX, indicating a prominent role for the A1 receptor. This interpretation is supported by the finding that adenosine- and CCPA-induced DNA synthesis is significantly inhibited by pertussis toxin, but substantially potentiated by PD81723, an allosteric enhancer of the A1 receptor. When a cDNA encoding the porcine A1 receptor was cloned and expressed in COS-1 cells, A1 receptor pharmacology is confirmed. Anti-sense oligonucleotides to the cloned sequence dramatically suppress the mitogenic effect of adenosine and CCPA. Conversely, over-expression of the cloned A1 receptor in CASMC increases adenosine- and CCPA-induced DNA synthesis. Furthermore, stimulation with adenosine or CCPA of intact coronary arteries in an organ culture model of vascular disease increases cellular DNA synthesis, which was abolished by DPCPX. We conclude that adenosine acts as a novel mitogen in porcine CASMC that express the A1 adenosine receptor, possibly contributing to the development of coronary artery disease.
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, School of Medicine, Columbia, Mo 65212, USA.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Shen
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Halenda
authors.forename: Michael
authors.initials: M
authors.lastname: Sturek
authors.forename: Peter A
authors.initials: PA
authors.lastname: Wilden
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D058916:Adenosine A1 Receptor Antagonists; D000595:Amino Acid Sequence; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003331:Coronary Vessels / Q000166:cytology / Q000378:metabolism*; D004247:DNA / Q000096:biosynthesis; D008934:Mitogens / Q000494:pharmacology; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D009924:Organ Culture Techniques; D037342:Pertussis Toxin / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D012333:RNA, Messenger / Q000378:metabolism; D043682:Receptor, Adenosine A1 / Q000235:genetics / Q000502:physiology*; D018047:Receptors, Purinergic P1 / Q000096:biosynthesis; D034421:Sus scrofa; D013876:Thiophenes / Q000494:pharmacology
chemical_list: D058916:Adenosine A1 Receptor Antagonists; D008934:Mitogens; D016376:Oligonucleotides, Antisense; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D012333:RNA, Messenger; D043682:Receptor, Adenosine A1; D018047:Receptors, Purinergic P1; D013876:Thiophenes; C075004:PD 81723; C048599:N(6)-cyclopentyladenosine; D004247:DNA; D037342:Pertussis Toxin; D000241:Adenosine