Treatment of Wistar rats for 7 days with
1,3-dipropyl-8-sulfophenylxanthine (
DPSPX), an antagonist of
adenosine receptors, induces long-lasting
hypertension associated with marked changes in vascular structure and reactivity and renin-angiotensin system activation. This study aimed at evaluating the role of oxidative stress in the development of
DPSPX-induced
hypertension and also at identifying the relative contribution of
superoxide radical (O2.-) vs
hydrogen peroxide (H2O2). Vascular and systemic prooxidant/
antioxidant status was evaluated in
sham (saline, i.p., 7 days) and
DPSPX (90 microg/kg/h, i.p., 7 days)-treated rats. Systolic blood pressure was determined by invasive and non-invasive methods. The activity of vascular
NADPH oxidase,
superoxide dismutase (SOD),
catalase and
glutathione peroxidase was assayed by fluorometric/spectrophotometric methods. H2O2 levels were measured using an
Amplex Red Hydrogen Peroxide kit. Plasma
thiobarbituric acid reactive substances and plasma
antioxidant capacity were also measured. In addition we tested the effects of
antioxidants or inhibitors of
reactive oxygen species generation on blood pressure, vascular
hyperplasia and oxidative stress parameters.
DPSPX-hypertensive rats showed increased activity of vascular
NADPH oxidase, SOD,
catalase and
glutathione peroxidase, as well as increased H2O2 generation.
DPSPX-hypertensive rats also had increased plasma lipid peroxidation and decreased plasma
antioxidant capacity. Treatment with
apocynin (1.5 mmol/l, per os, 14 days), or with
polyethylene glycol (
PEG)-catalase (10,000 U/kg/day, i.p., 8 days), prevented the
DPSPX-induced effects on blood pressure, vascular structure and H2O2 levels.
Tempol (3 mmol/l, per os, 14 days) failed to inhibit these changes, unless
PEG-catalase was co-administered. It is concluded that O2.- generation with subsequent formation of H2O2 plays a major role in the development of
DPSPX-induced
hypertension.