title: Relationship of muscle sympathetic nerve activity to insulin sensitivity.
abstract: OBJECTIVE
  An association between insulin resistance and activation of the sympathetic nervous system has been reported in previous studies. However, potential interactions between insulin sensitivity and sympathetic neural mechanisms in healthy people remain poorly understood. We conducted a study to determine the relationship between sympathetic activity and insulin resistance in young, healthy humans.
  
  
  METHODS
  Thirty-seven healthy adults (18-35 years, BMI <28 kg m(-2)) were studied. Resting muscle sympathetic nerve activity (MSNA) was measured with microneurography and insulin sensitivity of glucose and free fatty acid metabolism was measured during a hyperinsulinemic-euglycemic clamp with two levels of insulin.
  
  
  RESULTS
  During lower doses of insulin, we found a small association between lower insulin sensitivity and higher MSNA (P < 0.05) but age was a cofactor in this relationship. Overall, we found no difference in insulin sensitivity between groups of low and high MSNA, but when women were analyzed separately, insulin sensitivity was lower in the high MSNA group compared with the low MSNA group of women.
  
  
  CONCLUSIONS
  These data suggest that MSNA and insulin sensitivity are only weakly associated with young healthy individuals and that age and sex may be important modifiers of this relationship.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA, curry.timothy@mayo.edu.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Curry
authors.forename: Casey N
authors.initials: CN
authors.lastname: Hines
authors.forename: Jill N
authors.initials: JN
authors.lastname: Barnes
authors.forename: Madhuri
authors.initials: M
authors.lastname: Somaraju
authors.forename: Rita
authors.initials: R
authors.lastname: Basu
authors.forename: John M
authors.initials: JM
authors.lastname: Miles
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Joyner
authors.forename: Nisha
authors.initials: N
authors.lastname: Charkoudian
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation*; D013564:Sympathetic Nervous System / Q000502:physiology*; D055815:Young Adult