title: Regional differences in sympathetic activation in lean and obese normotensive individuals with obstructive sleep apnoea.
abstract: OBJECTIVE
  Obstructive sleep apnoea (OSA) is characterized by a marked sympathetic overdrive, as documented by the elevated sympathetic nerve firing rate detected in peripheral muscle nerves. No data are available, however, on the behaviour of sympathetic drive in vascular regional districts other than the muscle circulation.
  
  
  METHODS
  In 66 middle-aged normotensive individuals classified according to BMI, waist-to-hip ratio and apnoea-hypopnea index as lean individuals without (n = 20) or with (n = 14) OSA and as obese individuals without (n = 13) or with (n = 19) OSA, we measured blood pressure, heart rate, muscle sympathetic nerve activity (MSNA) and skin sympathetic nerve activity (SSNA), respectively, via microneurography. Measurements also included SSNA responses to an emotional stimulus.
  
  
  RESULTS
  The four groups were matched for age, sex and blood pressure values. Both in lean and obese individuals, presence of OSA was accompanied by MSNA values significantly greater than those found in non-OSA individuals. In contrast, no significant difference was found in SSNA values between OSA and non-OSA patients both in the lean and in the obese groups. This was the case also for the SSNA responses to an emotional arousal.
  
  
  CONCLUSIONS
  These data provide the first evidence that in OSA, the adrenergic overdrive seen in the muscle circulation is not detected in cutaneous circulation and thus it cannot be regarded as a generalized phenomenon affecting the whole cardiovascular system. Further studies are needed to clarify whether in OSA, sympathetic drive of other vascular districts, such as the coronary, renal or cerebral circulation, is activated or normal.
authors.affiliation: aClinica Medica, Dipartimento di Sanità e Salute Pubblica, Universita' Milano-Bicocca, Monza bIRCCS Multimedica, Sesto San Giovanni cIstituto Auxologico Italiano dCardiologia IV Ospedale Niguarda, Milan, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Grassi
authors.forename: Gino
authors.initials: G
authors.lastname: Seravalle
authors.forename: Gianmaria
authors.initials: G
authors.lastname: Brambilla
authors.forename: Silvia
authors.initials: S
authors.lastname: Buzzi
authors.forename: Marco
authors.initials: M
authors.lastname: Volpe
authors.forename: Francesca
authors.initials: F
authors.lastname: Cesana
authors.forename: Raffaella
authors.initials: R
authors.lastname: Dell'oro
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancia
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000294:innervation; D009765:Obesity / Q000150:complications* / Q000473:pathology / Q000503:physiopathology*; D009928:Organ Specificity; D012867:Skin / Q000294:innervation; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000473:pathology / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013851:Thinness / Q000150:complications / Q000473:pathology / Q000503:physiopathology