title: Gender differences in muscle sympathetic nerve activity: effect of body fat distribution.
abstract: Muscle sympathetic nerve activity (MSNA) has been correlated with percent body fat (%BF) in males. Because MSNA is typically lower and %BF higher in females, we tested whether this relationship could be generalized to females. Because abdominal-visceral body fat in men may be responsible for elevated sympathetic activity, we hypothesized that an estimate [waist-to-thigh ratio (W/T)] would correlate positively with MSNA in both genders and account for higher MSNA in males. Microneurography, hydrodensitometry, and W/T measures were obtained in 14 males and 14 females with a large range of %BF and W/T. Regression analyses revealed positive correlations between MSNA and %BF in males (r = 0.55, P = 0.04) and in females (r = 0.63, P = 0.02), with no difference in the slopes of the regression lines but a higher intercept in males (P < 0.01). When genders were pooled, MSNA and W/T were correlated (r = 0.68, P < 0.0001); this positive correlation was also found in males (r = 0.57, P = 0.04) but not as strongly in females (r = 0.49, P = 0.07). Forward stepwise multiple-regression analysis using %BF, W/T, gender, and age indicated that W/T was the primary factor related to MSNA (R2 = 0.46); the other factors were not independent predictors. It is concluded that %BF is related to MSNA in both males and females but that the regression line is shifted downward in females because of lower levels of MSNA. W/T is a better correlate of MSNA than %BF and partially explains the higher MSNA in males. These findings may be relevant to the cardiovascular and metabolic disease risk associated with abdominal obesity.
authors.affiliation: Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona, 85016, USA.
authors.forename: P P
authors.initials: PP
authors.lastname: Jones
authors.forename: S
authors.initials: S
authors.lastname: Snitker
authors.forename: J S
authors.initials: JS
authors.lastname: Skinner
authors.forename: E
authors.initials: E
authors.lastname: Ravussin
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D000886:Anthropometry; D001823:Body Composition; D005260:Female; D006801:Humans; D008297:Male; D009132:Muscles / Q000294:innervation*; D012044:Regression Analysis; D012727:Sex Characteristics; D013564:Sympathetic Nervous System / Q000502:physiology*; D013848:Thigh / Q000033:anatomy & histology