Up-regulation of endothelin type B receptors in the human internal mammary artery in culture is dependent on protein kinase C and mitogen-activated kinase signaling pathways.
BACKGROUND
Up-regulation of vascular endothelin type B (ETB) receptors is implicated in the pathogenesis of cardiovascular disease. Culture of intact arteries has been shown to induce similar receptor alterations and has therefore been suggested as a suitable method for, ex vivo, in detail delineation of the regulation of endothelin receptors. We hypothesize that mitogen-activated kinases (MAPK) and protein kinase C (PKC) are involved in the regulation of endothelin ETB receptors in human internal mammary arteries.


METHODS
Human internal mammary arteries were obtained during coronary artery bypass graft surgery and were studied before and after 24 hours of organ culture, using in vitro pharmacology, real time PCR and Western blot techniques. Sarafotoxin 6c and endothelin-1 were used to examine the endothelin ETA and ETB receptor effects, respectively. The involvement of PKC and MAPK in the endothelin receptor regulation was examined by culture in the presence of antagonists.


RESULTS
The endothelin-1-induced contraction (after endothelin ETB receptor desensitization) and the endothelin ETA receptor mRNA expression levels were not altered by culture. The sarafotoxin 6c contraction, endothelin ETB receptor protein and mRNA expression levels were increased after organ culture. This increase was antagonized by; (1) PKC inhibitors (10 microM bisindolylmaleimide I and 10 microM Ro-32-0432), and (2) inhibitors of the p38, extracellular signal related kinases 1 and 2 (ERK1/2) and C-jun terminal kinase (JNK) MAPK pathways (10 microM SB203580, 10 microM PD98059 and 10 microM SP600125, respectively).


CONCLUSIONS
In conclusion, PKC and MAPK seem to be involved in the up-regulation of endothelin ETB receptor expression in human internal mammary arteries. Inhibiting these intracellular signal transduction pathways may provide a future therapeutic target for hindering the development of vascular endothelin ETB receptor changes in cardiovascular disease.
Nilsson
David
D
Department of Medicine, Lund University Hospital, Sweden. david.nilsson@med.lu.se
Gustafsson
Lotta
L
Wackenfors
Angelica
A
Gesslein
Bodil
B
Edvinsson
Lars
L
Paulsson
Per
P
Ingemansson
Richard
R
Malmsjö
Malin
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects / Q000201:enzymology*; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D046509:Tissue Culture Techniques; D015854:Up-Regulation; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D019332:Endothelin-1; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D014662:Vasoconstrictor Agents; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases
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