Calcium antagonist reduces oxidative stress by upregulating Cu/Zn superoxide dismutase in stroke-prone spontaneously hypertensive rats.
Recent studies have suggested that the calcium antagonists have an antiatherogenic antioxidant property. The effects of the calcium antagonists on reactive oxygen species (ROS)-related enzymes, however, remain unknown. We hypothesized that the calcium antagonists inhibit oxidative stress in the hearts of stroke-prone spontaneously hypertensive rats (SHRSP) through the ROS-scavenging enzymes known as superoxide dismutases (SODs). Male 12-week-old Wister-Kyoto rats (WKY) and SHRSP were used for the study. SHRSP were randomized and treated for 6 weeks with a vehicle, amlodipine (5 mg/kg/day), or enalapril (10 mg/kg/day). NAD(P)H oxidase activity was measured by a luminescence assay, and SOD activity was measured spectrophotometrically. Protein expressions were analyzed by immunoblots. Both drugs showed equipotent effects on systolic blood pressure, left ventricular hypertrophy and fibrosis, the wall-to-lumen ratio, the manganese SOD activity, ROS, and the endothelial NO synthase expression in the SHRSP hearts. Furthermore, amlodipine significantly restored copper/zinc-containing SOD (Cu/ZnSOD) expression and its activity in SHRSP hearts to a level equal to that of WKY more effectively than did enalapril (p <0.05), whereas enalapril downregulated NAD(P)H oxidase activity more than did amlodipine (p <0.05) in the SHRSP hearts. Furthermore, amlodipine restored Cu/ZnSOD expression and its activity in SHRSP hearts to a level equal to that in WKY hearts, and this restoration was significantly more effective than that by enalapril (p <0.05); on the other hand, enalapril induced a greater downregulation of NAD(P)H oxidase activity in SHRSP hearts than did amlodipine (p <0.05). Thus, amlodipine may inhibit vascular remodeling and oxidative stress in the SHRSP heart by efficiently upregulating Cu/ZnSOD, suggesting that the calcium antagonist may exhibit an antiatherogenic antioxidative action beyond blood-pressure lowering through the restoration of Cu/ZnSOD activity in the heart in cases of hypertension.
Umemoto
Seiji
S
Pharmaceutical Clinical Research Center, Yamaguchi University Hospital, Ube, Japan. umemoto@yamaguchi-u.ac.jp
Tanaka
Masakazu
M
Kawahara
Shinji
S
Kubo
Makoto
M
Umeji
Kyoko
K
Hashimoto
Ryo
R
Matsuzaki
Masunori
M
D017311:Amlodipine / Q000494:pharmacology*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects; D004656:Enalapril / Q000494:pharmacology; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000201:enzymology; D019255:NADPH Oxidases / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D020521:Stroke / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
D000806:Angiotensin-Converting Enzyme Inhibitors; D002121:Calcium Channel Blockers; D017311:Amlodipine; D004656:Enalapril; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D013482:Superoxide Dismutase; D019255:NADPH Oxidases