Apocynin normalizes hyperreactivity to phenylephrine in mesenteric arteries from cholesterol-fed mice by improving endothelium-derived hyperpolarizing factor response.
We studied the relationship among endothelial function, oxidative stress, and phenylephrine (PE; alpha(1)-adrenoceptor agonist)-induced contraction in mesenteric arteries from high-cholesterol (HC)-diet-fed mice. In HC mice (vs age-matched normal-diet-fed mice): (1) PE-induced contraction in endothelium-intact rings was enhanced (endothelial denudation increased contraction in "normal-diet" rings, but did not enhance it further in "HC" rings); (2) the enhanced PE-induced contraction was further enhanced in the presence of N(G)-nitro-L-arginine (L-NNA; nitric oxide synthase inhibitor) or L-NNA plus indomethacin (cyclooxygenase inhibitor) [to preserve endothelium-derived hyperpolarizing factor (EDHF)], but unchanged in the presence of charybdotoxin plus apamin (to block EDHF); (3) ACh-induced EDHF-type relaxation was reduced; and (4) oxidative stress [indicated by the plasma 8-isoprostane level (reliable systemic marker) and aortic superoxide production] was greater. In HC mice, PE-induced contraction was normalized by apocynin [NAD(P)H oxidase inhibitor] or tempol (superoxide dismutase mimetic), but enhanced by NADH [NAD(P)H oxidase substrate]. Oral dietary supplementation with apocynin (30 mg/kg/day for 4 weeks) corrected the above abnormalities. Hence: (1) PE-induced contraction is modulated by the endothelium, and the enhanced contractility in HC mice results from defective EDHF signaling and elevated oxidative stress, and (2) apocynin normalizes PE-induced contraction in HC mice by improving EDHF signaling.
Matsumoto
Takayuki
T
Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan.
Miyamori
Kiyoto
K
Kobayashi
Tsuneo
T
Kamata
Katsuo
K
D000098:Acetophenones / Q000494:pharmacology*; D000109:Acetylcholine / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001685:Biological Factors / Q000502:physiology*; D002791:Cholesterol, Dietary / Q000008:administration & dosage; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006937:Hypercholesterolemia / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008813:Mice, Inbred ICR; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010656:Phenylephrine / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects
D000098:Acetophenones; D000316:Adrenergic alpha-Agonists; D001685:Biological Factors; D002791:Cholesterol, Dietary; D004791:Enzyme Inhibitors; C067410:endothelium-dependent hyperpolarization factor; D013481:Superoxides; D009599:Nitroprusside; D010656:Phenylephrine; C075750:8-epi-prostaglandin F2alpha; C056165:acetovanillone; D015237:Dinoprost; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D019255:NADPH Oxidases; D000109:Acetylcholine; D011188:Potassium