Sympathetic activity and markers of cardiovascular risk in nondiabetic severely obese patients: the effect of the initial 10% weight loss.
BACKGROUND
Obesity is associated with elevated cardiovascular mortality, which may be attributed, in part, to sympathetic nervous system (SNS) activation and an associated poor metabolic profile. We examined the effects of laparoscopic adjustable gastric band (LAGB) on SNS activity and cardiovascular profile when the initial weight loss of 10%, corresponding to the recommendation of clinical guidelines, was reached.


METHODS
Direct muscle sympathetic nerve activity (MSNA, microneurography), baroreflex function, and cardiovascular profile were examined before and after a predetermined weight loss of 10% in 23 severely obese nondiabetic individuals.


RESULTS
The 10% weight loss was achieved at an average of 7.3 ± 1.4 months (range = 1.3-23.3 months). This was associated with significant improvement in office systolic and diastolic blood pressure (BP) (-12 mm Hg and -5 mm Hg, respectively), a decrease in MSNA (33 ± 3 to 22 ± 3 bursts per minute), improvement in cardiac (16 ± 3 to 31 ± 4 ms/mm Hg) and sympathetic (-2.23 ± 0.39 to -4.30 ± 0.96 bursts/100 heartbeats/mm Hg) baroreflex function, total cholesterol (5.33 ± 0.13 to 4.97 ± 0.16 mmol/L), fasting insulin (29.3 ± 2.4 to 19.6 ± 1.1 mmol/L), and creatinine clearance (172 ± 11 to 142 ± 8 ml/min). None of the cardiovascular risk improvement related to the rate of weight loss. The change in systolic and diastolic BP correlated with change in waist circumference (r = 0.46, P = 0.04; r = 0.50, P = 0.02, respectively).


CONCLUSIONS
The initial 10% weight loss induced by LAGB was associated with substantial hemodynamic, metabolic, SNS, and renal function improvements. Changes in waist circumference appear to be an important factor contributing to BP adaptation after LAGB surgery.
Human Neurotransmitters, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia; Department of Physiology, Monash University, Melbourne, Victoria, Australia; Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia;
Elisabeth A
EA
Lambert
Clinical Obesity Research, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia;
Toni
T
Rice
Human Neurotransmitters, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia;
Nina
N
Eikelis
Human Neurotransmitters, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia;
Nora E
NE
Straznicky
Human Neurotransmitters, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia; Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia;
Gavin W
GW
Lambert
Department of Physiology, Monash University, Melbourne, Victoria, Australia; Neuropharmacology, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia;
Geoffrey A
GA
Head
Lap-Surgery Australia, Boronia, Victoria;
Chris
C
Hensman
Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia; Neurovascular Hypertension & Kidney Disease Laboratories, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia;
Markus P
MP
Schlaich
Clinical Obesity Research, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia; Primary Health Care and the Department of Cardiovascular Medicine, Alfred Hospital, Melbourne, Victoria, Australia. john.dixon@bakeridi.edu.au.
John B
JB
Dixon
D000328:Adult; D050110:Bariatric Surgery; D017704:Baroreflex / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D009767:Obesity, Morbid / Q000503:physiopathology / Q000601:surgery*; D017779:Sympathetic Fibers, Postganglionic / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D015431:Weight Loss / Q000502:physiology*; D055815:Young Adult
bariatric surgery; blood pressure; glomerular filtration; hypertension; obesity; sympathetic nervous system.