A Novel Adipocytokine, Omentin, Inhibits Agonists-Induced Increases of Blood Pressure in Rats

Abstract

ABSTRACT. Omentin is a recently identified adipocytokine, and we previously demonstrated that omentin played anti-inflammatory roles in vascular endothelial and smooth muscle cells. We also demonstrated that omentin induced vasodilation in rat isolated blood vessels. However, effects of omentin on blood pressure (BP) Adipocytes can secrete a variety of cytokines, termed adipocytokine. Obesity with an accumulation of visceral fat is one of the main risk factors for cardiovascular diseases, including hypertension. Adipocytes enlarged by obesity may increase or decrease the production and secretion of adipocytokine. Adipocytokine is thought to regulate obesity-related hypertension by directly acting on vascular system [13,14].Omentin is a recently identified adipocytokine consisting of 313 amino acids [9]. Secretion and plasma concentration of omentin decrease in the obese patients, but increase after a weight loss [2]. We previously demonstrated that omentin was anti-inflammatory in cultured vascular endothelial and smooth muscle cells [5,16]. In addition, we demonstrated that omentin induced vasodilation in rat isolated blood vessels via stimulating endothelial nitric oxide (NO) production [15]. While it is presumed that omentin could regulate blood pressure (BP) in vivo, effects of omentin on BP remain to be determined. Here, we for the first time provided the evidence that omentin can regulate BP in rats. MATERIALS AND METHODS Materials:Reagent sources were as follows: recombinant omentin (BioVendor, Candler, NC, U.S.A.); noradrenaline (NA) and angiotensin II (Ang II) (Sigma-Aldrich, St. Louis, MO, U.S.A.); dimorpholamine (Eisai Co., Ltd., Tokyo, Japan); N G -nitro-l-arginine methyl ester (L-NAME) (Dojindo, Kumamoto, Japan).Physical parameters of rats: Physical parameters of normal Wistar rats (Clea Japan Inc., Tokyo, Japan) or L-NAME-treated Wistar rats (6-10-week-old) were measured. Body weight, heart rate (HR), systolic blood pressure (BP) (SBP), mean BP (MBP) and diastolic BP (DBP) represent the average value (Table 1). Noninvasive BP in conscious rats was measured using a tail-cuff method after heating the rats (38°C) (Softron, Tokyo, Japan) [6,11,12]. L-NAME was dissolved in drinking water and given to rats (80 mg/kg, 1 day).Direct BP measurement: BP and HR of male Wistar rats (130-350 g, 6-10-week-old) were measured under urethane (1.5 g/kg, i.p.) anesthesia as described previously [7,17]. Briefly, the catheter filled with a heparin-saline solution was inserted into carotid artery with a small incision. Catheter was connected to MLT0670 BP transducer (ADInstruments, Colorado Springs, CO, U.S.A.). SBP, MBP and DBP were measured and recorded using ML117 BP Amp (ADInstruments), ML825 PowerLab 2/25 (ADInstruments) system and Chart5 software (ADInstruments). HR was calculated by a cyclic measurement of BP recording. After omentin (0.06-1.8 µg/kg) or saline was intravenously applied for 5 min through the catheter inserted into saphenous vein, NA (0.02-2 µg/kg), Ang II (0.01-10 µg/kg) or dimorpholamine (3 mg/...

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A novel adipocytokine, omentin, inhibits platelet-derived growth factor-BB-induced vascular smooth muscle cell migration through antioxidative mechanism

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Association of Circulating Omentin-1 with Osteoporosis in a Chinese Type 2 Diabetic Population

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