Upregulation of proteinase-activated receptor-2 and increased response to trypsin in endothelial cells after exposure to oxidative stress in rat aortas.
OBJECTIVE
The effects of oxidative stress on the vascular responsiveness to the agonists of proteinase-activated receptors (PARs) were investigated.


METHODS
Serum-free incubation was utilized to impose oxidative stress to isolated rat aortas. Spontaneously hypertensive rats (SHR) were investigated as a model of in vivo oxidative stress.


RESULTS
Thrombin, trypsin, PAR₁-activating peptide (PAR₁-AP), PAR₂-AP and PAR₄-AP induced little or no effect in the aortas of female Wistar-Kyoto rats (WKY). Serum-free incubation induced endothelium-dependent relaxant responses to PAR₂ agonists, but not PAR₁ or PAR₄ agonists, in a manner sensitive to diphenyleneiodonium or ascorbic acid. In male aortas, trypsin and PAR₂-AP induced a transient endothelium-dependent relaxation without serum-free incubation. The acetylcholine-induced endothelium-dependent relaxation and the sodium nitroprusside-induced endothelium-independent relaxation remained unchanged. Immunoblot analyses revealed the upregulation of PAR₂ in endothelial cells, which was abolished by either diphenyleneiodonium or ascorbic acid. Aortas of female SHR expressed a higher level of PAR₂ than WKY and responded to trypsin without serum-free incubation. Treatment with ascorbic acid attenuated the trypsin-induced relaxation and the PAR₂ expression in SHR.


CONCLUSIONS
This study provides the first evidence that oxidative stress upregulates PAR₂ in endothelial cells, thereby enhancing the endothelium-dependent relaxant response to PAR₂ agonists in rat aortas.
Aman
Murasaki
M
Division of Molecular Cardiology, Research Institute of Angiocardiology, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
Hirano
Mayumi
M
Kanaide
Hideo
H
Hirano
Katsuya
K
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001011:Aorta / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D016895:Culture Media, Serum-Free; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D006973:Hypertension / Q000201:enzymology* / Q000503:physiopathology; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D044464:Receptor, PAR-2 / Q000819:agonists / Q000378:metabolism*; D013997:Time Factors; D046509:Tissue Culture Techniques; D014357:Trypsin / Q000378:metabolism*; D015854:Up-Regulation; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D000975:Antioxidants; D016895:Culture Media, Serum-Free; D009842:Oligopeptides; D044464:Receptor, PAR-2; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C112356:seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide; D014357:Trypsin