Acute production of vascular superoxide by angiotensin II but not by catecholamines.
OBJECTIVE
To determine whether vascular superoxide is rapidly released by angiotensin II and is involved in vascular contraction.


METHODS
The effect of superoxide dismutase (SOD) on angiotensin II induced elevation of mean arterial blood pressure was measured. Subsequently, acute production of vascular superoxide by angiotensin II and its effect on isometric tension were measured in rat aortic rings. The effects of catecholamines were concomitantly measured.


RESULTS
The acute pressor effects of angiotensin II were significantly reduced when rats were pretreated intravenously with SOD. When angiotensin II was added on aortic segments in the presence of Cypridina luciferin analog, immediate elevations of chemiluminescence were observed which were inhibited by SOD. Furthermore, angiotensin II-induced elevations of isometric tension in aortic rings were significantly reduced by SOD. The effects of epinephrine and norepinephrine were concomitantly measured and were not significant


CONCLUSIONS
The acute superoxide producing effect is likely to be specific to angiotensin II, because such a significant modification of the effects was not observed for catecholamines. Our results suggest that angiotensin II causes acute vascular superoxide production, which may be involved in the acute pressor effects.
Kawazoe
T
T
Department of Plastic Surgery, Kagawa Medical University, Kita, Japan.
Kosaka
H
H
Yoneyama
H
H
Hata
Y
Y
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004837:Epinephrine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011921:Rats, Inbred WKY; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D013481:Superoxides; D000804:Angiotensin II; D013482:Superoxide Dismutase; D009638:Norepinephrine; D004837:Epinephrine