Hydroxyl radical mediates the augmented angiotensin II responses in thoracic aorta of spontaneously hypertensive rats.
OBJECTIVE
To investigate the role of hydroxyl radical in augmented angiotensin II (Ang II) responses in the thoracic aorta of spontaneously hypertensive rats (SHR).


METHODS
To elucidate the role of hydroxyl radical, we used edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) as a tool for our study. The vascular responses to Ang II (10(-10) to 10(-6) mol/l), tert-butyl hydroperoxide (tBHP; 10(-6) to 10(-2) mol/l) and H(2)O(2) (10(-6) to 10(-2) mol/l) were constructed in aortic preparations obtained from control (WKY) and SHR in the absence and presence of edaravone.


RESULTS
The vascular responses to Ang II, tBHP and H(2)O(2) were found to be enhanced in aortic preparations from SHR as compared to control WKY rats. Edaravone selectively attenuated the augmented responses to Ang II but not to tBHP and H(2)O(2) suggesting that the .OH radical is involved in the augmented responses to Ang II. The elevated blood pressure in SHR was restored to a near normal value after 2 weeks of edaravone (10 mg kg(-1) i.p., b.i.d.) treatment.


CONCLUSIONS
From the results we infer that hydroxyl radical stress augments Ang II responses in the thoracic aorta of SHR and, by attenuating these enhanced vascular responses, edaravone could serve as an adjuvant antioxidant therapy for the vascular complications of hypertension.
Deshmukh
Aaishwarya B
AB
Department of Pharmacology, S.K. Patel College of Pharmaceutical Education and Research, Kherva, India.
Patel
Natvarlal J
NJ
Patel
Rashwin J
RJ
D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives / Q000494:pharmacology; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D000077553:Edaravone; D016166:Free Radical Scavengers / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D010545:Peroxides / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014661:Vasoconstriction; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
D016166:Free Radical Scavengers; D010545:Peroxides; D000804:Angiotensin II; D017665:Hydroxyl Radical; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D000077553:Edaravone; D000983:Antipyrine