Abstract 17226: Vascular Smooth Muscle Responsiveness to a Nitric Oxide Donor is Impaired in Healthy Adults with Increased Adiposity
Background- Vascular smooth muscle responsiveness to an exogenous nitric oxide donor (i.e., nitroglycerin-induced dilation; NID) is impaired in cardiovascular disease and in adults at risk for atherosclerosis. Although adiposity is associated with increased risk of atherosclerosis, its relation to NID is poorly defined. We sought to examine the relation of NID to total and abdominal adiposity in a healthy group of men and women varying widely in adiposity levels and age.
Methods and Results- In 224 carefully screened adults (age:18-79 yrs, body mass index (BMI): 16.4-42.2 kg/m2), we measured NID, total body adiposity (BMI and % body fat (%BF); dual-energy x-ray absorptiometry) and indices of abdominal adiposity (waist circumference (WC) and waist to hip ratio (WHR)). In a subgroup of 74 subjects, we also measured total abdominal (TAF), abdominal visceral (AVF) and subcutaneous fat (ASF) using CT scans. NID was determined as the vasodilator response (brachial ultrasonography) to 0.4 mg sublingual nitroglycerin. Based on multiple linear regression analyses, NID was negatively related to BMI (part correlation coefficient (rpart)=-0.19, P=0.004) and not related with total %BF (rpart=-0.12, P=0.07), whereas it was consistently negatively related with abdominal adiposity (WC, rpart=-0.22; WHR, rpart=-0.19; TAF, rpart=-0.36; AVF, rpart=-0.36; and ASF, rpart=-0.30, all P≤0.009), independent of sex. Accounting for systolic blood pressure, high density lipoprotein (HDL) cholesterol and fasting blood glucose reduced all of the sex-independent relations between NID and adiposity by 3 to 42%, but overall the relations remained significant (P≤0.05). NID was 35% lower in a subgroup of subjects with the highest compared to the lowest quintile of abdominal visceral fat (P=0.003). This difference in NID was abolished after accounting for systolic blood pressure (P=0.2) and HDL cholesterol (P=0.1) but was not changed after accounting for fasting glucose (P=0.002).
Conclusions- Total adiposity is modestly (BMI) or not related (% body fat) with NID, whereas abdominal adiposity is more consistently and strongly related with NID. Adiposity may influence NID in part via modulation of blood pressure, HDL cholesterol and/or fasting glucose.
- © 2011 by American Heart Association, Inc.