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Endogenous hydrogen peroxide is vasoactive in mesenteric arteries of spontaneously hypertensive rat
Author(s) -
Kroetsch Jeffrey Thomas,
Rush James W.E.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1154.5
Subject(s) - dilator , mesenteric arteries , endocrinology , medicine , nitric oxide , incubation , vasodilation , nitric oxide synthase , chemistry , artery , biochemistry
Hydrogen peroxide (H 2 O 2 ) is an endogenous endothelium‐dependent dilator in resistance vessels; however, a role for H 2 O 2 in the mesenteric vessels of the spontaneously hypertensive rat (SHR) has not been established. Mesenteric arteries were excised from SHR and normotensive (WKY) rats and myography was performed. Vessels were incubated with 3μM of the β‐blocker propranolol, pre‐contracted with norepinephrine, and cumulative dose‐response curves for acetylcholine (Ach) were conducted. Maximal dilation to Ach was impaired in SHR compared to WKY (76±4% vs 97±1%, p<0.05). Co‐incubation with the nitric oxide synthase inhibitor N ω ‐nitro‐L‐arginine (L‐NAME, 0.3mM) and the cyclooxygenase inhibitor indomethacin (INDO, 5μM) reduced dilation in SHR (52±6%, p<0.05). Co‐incubation with L‐NAME, INDO, and the H 2 O 2 scavenger catalase (CAT, 860U/mL) caused a further reduction in SHR dilation (32±3%, p<0.05). Incubation with CAT alone caused improved dilation (92±12%, p<0.05) while incubation with the superoxide dismutase mimetic 4‐hydroxy‐TEMPO (1mM) reduced dilation (59±7%, p=0.05) in SHR. WKY dilation was not altered by any treatment. Thus, in the presence of nitric oxide and prostaglandins, H 2 O 2 acts as a constrictor; however, in the absence of nitric oxide and prostaglandins, H 2 O 2 acts as a dilator in SHR mesenteric arteries. Funding: NSERC/Heart and Stroke Foundation of Ontario