Concomitantly higher resting arterial blood pressure and transduction of sympathetic neural activity in human obesity without hypertension

Abstract

Objective: Central (abdominal) obesity is associated with elevated adrenergic activity and arterial blood pressure (BP). Therefore, we tested the hypothesis that transduction of spontaneous muscle sympathetic nerve activity (MSNA) to BP, that is, sympathetic transduction, is augmented in abdominal obesity (increased waist circumference) and positively related to prevailing BP.Methods: Young/middle-aged obese (32 AE 7 years; BMI: 36 AE 5 kg/m 2 , n ¼ 14) and nonobese (29 AE 10 years; BMI: 23 AE 4 kg/m 2 , n ¼ 14) without hypertension (24-h ambulatory average BP < 130/80 mmHg) were included. MSNA (microneurography) and beat-to-beat BP (finger cuff) were measured continuously and the increase in mean arterial pressure (MAP) during 15 cardiac cycles following MSNA bursts of different patterns (single, multiples) and amplitude (quartiles) was signal-averaged over a 10 min baseline period.Results: MSNA burst frequency was not significantly higher in obese vs. nonobese (21 AE 3 vs. 17 AE 3 bursts/min, P ¼ 0.34). However, resting supine BP was significantly higher in obese compared with nonobese (systolic: 127 AE 3 vs. 114 AE 3; diastolic: 76 AE 2 vs. 64 AE 1 mmHg, both P < 0.01). Importantly, obese showed greater increases in MAP following multiple MSNA bursts (P ¼ 0.02) and MSNA bursts of higher amplitude (P ¼ 0.02), but not single MSNA bursts (P ¼ 0.24), compared with nonobese when adjusting for MSNA burst frequency. The increase in MAP following higher amplitude bursts among all participants was associated with higher resting supine systolic (R ¼ 0.48; P ¼ 0.01) and diastolic (R ¼ 0.48; P ¼ 0.01) BP when controlling for MSNA burst frequency, but not when also controlling for waist circumference (P > 0.05). In contrast, sympathetic transduction was not correlated with 24-h ambulatory average BP. Conclusion:Sympathetic transduction to BP is augmented in abdominal obesity and positively related to higher resting supine BP but not 24-h ambulatory average BP.

Could METS-VF provide a clue as to the formation of kidney stones?

“…Having an elevated Body Mass Index (BMI) is the most commonly used way to gauge if one is at risk of forming kidney stones ( 7 , 8 ), which can be caused by being overweight. However, BMI is not without its drawbacks ( 9 ).…”

Study from the United States: increased prevalence of kidney stones in patients with high weight-adjusted waist index

“…The analysis of the Health Professionals Follow-up Study and the Nurses’ Health Study I and II identified associations between obesity, diabetes, and kidney stone disease ( 8 , 9 ). Currently, the most commonly used measure of obesity is BMI (Body Mass Index) ( 10 ). However, BMI has some limitations, such as the inability to distinguish between lean body mass and fat body weight ( 11 ).…”