Atherosclerosis 190 (2007) 436–442 Nitric oxide production is paradoxically decreased after weight reduction surgery in morbid obesity patients Lian-Yu Lin a , Wei-Jei Lee b , Hsiu-Nien Shen c , Wei-Shiung Yang a , Ni-Hao Pai d , Ta-Chen Su a,e,∗ , Chiau-Suong Liau a,∗∗ a Divisions of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taiwan b Department of Surgery, En-Chu-Kong General Hospital, Taiwan c Department of Intensive Care Medicine, Chi Mei Medical Center, Taiwan d Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Yunlin Branch, Taiwan e Institute of Industrial Hygiene and Occupational Medicine, College of Public Health, National Taiwan University, Taiwan Received 5 August 2005; received in revised form 5 February 2006; accepted 12 February 2006 Available online 20 March 2006 Abstract Obesity is associated with vascular endothelial cell dysfunction (ECD). Studies on nitric oxide (NO) production of vascular system in these subjects may help delineate the pathogenesis of obesity-associated ECD. In this study, we recruited 69 severely obese patients who were treated with gastric partition surgery for weight reduction and 69 matched healthy controls for comparison. The following param- eters were obtained in the healthy control subjects and in the obese subjects both before and after gastric partition surgery: body mass index, blood pressure, serum lipids, high sensitivity C-reactive protein (hs-CRP), adiponectin, total nitrite and nitrate (NO x ), and 8-iso- prostaglandin F2 (8-iso-PGF2), and insulin resistance index (as measured by homeostasis model assessment (HOMA-IR). At baseline, serum lipids, glucose, insulin, hs-CRP and 8-iso-PGF2 and HOMA-IR were all higher while adiponectin lower in the obese group than in the control group. The serum NO x levels were not different between the two groups. In the obese subjects, the adiponectin levels were significantly elevated but NO x markedly decreased after surgery. All other measurements, except for systolic blood pressure, were decreased after surgery. For healthy controls, the serum NO x levels were negatively associated with HOMA-IR and positively associated with serum adiponectin levels as analyzed by multiple linear regression analysis. In obese patients, the baseline serum NO x was positively associated with the serum TG levels. The changes of serum NO x levels after weight reduction surgery were positively associated with the changes of body mass index and serum TG levels. These observations suggested that, in the extremely obese patients, there might be excessive production and/or inactivation of NO and, after weight reduction surgery, the NO production was down-regulated. In conclu- sion, in the severely obese patients, the apparently normal NO production might be due to over-expression of iNOS. After gastric partition surgery, the NO production was significantly decreased which might be reflecting the usual status of NO production in obese subjects. The positive correlation between NO x and serum TG level might suggest that the metabolism of TG plays a role in the regulation of NO production. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Nitric oxide production; Weight reduction surgery; Morbid obesity; Endothelial cell function; Oxidative stress ∗ Corresponding author at: Department of Internal Medicine, National Taiwan University Hospital and Medical College of National Taiwan University, 7 Chung-Shan South Road, Taipei 100, Taiwan. Tel.: +886 2 23123456x6719; fax: +886 2 23712361. ∗∗ Corresponding author at: Department of Internal Medicine, National Taiwan University Hospital and Medical College of National Taiwan University, 7 Chung-Shan South Road, Taipei 100, Taiwan. Tel.: +886 2 23123456x5033; fax: +886 2 23935346. E-mail addresses: tachensu@ha.mc.ntu.edu.tw (T.-C. Su), csliau@ha.mc.ntu.edu.tw (C.-S. Liau). 0021-9150/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.atherosclerosis.2006.02.033