title: Severe obesity is associated with impaired arterial smooth muscle function in young adults.
abstract: The degree of arterial dilatation induced by exogenous nitrates (nitrate-mediated dilatation, NMD) has been similar in obese and normal-weight adults after single high-dose glyceryl trinitrate (GTN). We examined whether NMD is impaired in obesity by performing a GTN dose-response study, as this is a potentially more sensitive measure of arterial smooth muscle function. In this cross-sectional study, subjects were 19 obese (age 31.0 ± 1.2 years, 10 male, BMI 44.1 ± 2.1) and 19 age- and sex-matched normal-weight (BMI 22.4 ± 0.4) young adults. Blood pressure (BP), triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL)-cholesterol, glucose, insulin, high-sensitivity C-reactive protein (hs-CRP), carotid intima-media thickness (CIMT), and flow-mediated dilatation (FMD) were measured. After incremental doses of GTN, brachial artery maximal percent dilatation (maximal NMD) and the area under the dose-response curve (NMD AUC) were calculated. Maximal NMD (13.4 ± 0.9% vs. 18.3 ± 1.1%, P = 0.002) and NMD AUC (54,316 ± 362 vs. 55,613 ± 375, P = 0.018) were lower in obese subjects. The obese had significantly higher hs-CRP, insulin, and CIMT and lower HDL-cholesterol. Significant bivariate associations existed between maximal NMD or NMD AUC and BMI-group (r = -0.492, P = 0.001 or r = -0.383, P = 0.009), hs-CRP (r = -0.419, P = 0.004 or r = -0.351, P = 0.015), and HDL-cholesterol (r = 0.374, P = 0.01 or r = 0.270, P = 0.05). On multivariate analysis, higher BMI-group remained as the only significant determinant of maximal NMD (r² = 0.242, β = -0.492, P = 0.002) and NMD AUC (r² = 0.147, β = -0.383, P = 0.023). In conclusion, arterial smooth muscle function is significantly impaired in the obese. This may be important in their increased cardiovascular risk.
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.
authors.forename: Julian G
authors.initials: JG
authors.lastname: Ayer
authors.forename: Jason A
authors.initials: JA
authors.lastname: Harmer
authors.forename: Clementine
authors.initials: C
authors.lastname: David
authors.forename: Katherine
authors.initials: K
authors.lastname: S Steinbeck
authors.forename: J Paul
authors.initials: JP
authors.lastname: Seale
authors.forename: David S
authors.initials: DS
authors.lastname: Celermajer
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D015992:Body Mass Index; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology*; D005996:Nitroglycerin / Q000494:pharmacology; D009767:Obesity, Morbid / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D058729:Peripheral Arterial Disease / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D012720:Severity of Illness Index; D014463:Ultrasonography; D014664:Vasodilation / Q000187:drug effects; D055815:Young Adult
chemical_list: D005996:Nitroglycerin