Abnormal neurovascular control during sympathoexcitation in obesity.
OBJECTIVE
We tested the hypothesis that muscle sympathetic nerve activity (MSNA) and forearm vascular resistance (FVR) would be augmented during mental stress or cold pressor test in healthy obese individuals compared with healthy lean individuals.


METHODS
Twenty-nine healthy obese women and 12 age-matched healthy lean women were involved in the study. MSNA was directly measured from the peroneal nerve using microneurography. Forearm blood flow was measured by venous occlusion plethysmography. Blood pressure (BP) was monitored noninvasively by an automatic BP cuff, and heart rate (HR) was measured by electrocardiogram. Stroop color word test was performed for 4 minutes, and the cold pressor test was performed for 2 minutes.


RESULTS
Baseline MSNA and FVR were greater in the obese group than in the lean group. BP and HR were similar between groups. During mental stress, MSNA and FVR were greater in obese individuals than in lean individuals, although the magnitude of response was similar between groups. BP and HR similarly increased in obese and lean individuals. During the cold pressor test, MSNA, FVR, and BP were greater in obese individuals, but the magnitude of response was similar between groups. HR increased similarly during the cold pressor test in both obese and lean individuals.


CONCLUSIONS
Obesity increases MSNA and FVR during mental stress and the cold pressor test. This inappropriate neurovascular control can be expected to have an adverse effect on the risk factors for cardiovascular events and, hence, should be considered in the treatment of obese patients.
Kuniyoshi
Fátima H S
FH
Heart Institute (InCor), Medical School, University of São Paulo, São Paulo CEP 05403-000, Brazil.
Trombetta
Ivani C
IC
Batalha
Luciana T
LT
Rondon
Maria U P B
MU
Laterza
Mateus C
MC
Gowdak
Márcia M G
MM
Barretto
Antonio C P
AC
Halpern
Alfredo
A
Villares
Sandra M F
SM
Lima
Eliudem G
EG
Negrão
Carlos E
CE
D000328:Adult; D001794:Blood Pressure; D003080:Cold Temperature; D005260:Female; D005542:Forearm / Q000098:blood supply; D006339:Heart Rate; D006801:Humans; D007101:Immersion; D009132:Muscles / Q000294:innervation*; D009765:Obesity / Q000503:physiopathology*; D010543:Peroneal Nerve / Q000503:physiopathology; D010991:Plethysmography; D013315:Stress, Psychological; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014655:Vascular Resistance