Transduction of Sympathetic Neural Activity in Human Obesity Without Hypertension

In addition to chronically elevated MSNA, there is a growing recognition that hypertension in states of insulin resistance and obesity may also be attributed to an increased vascular sensitivity to MSNA (1, 2, 13, 36-38). To study this phenomenon, we quantify vascular sensitivity to MSNA using an innovative, moment-to-moment assessment of the blood pressure response following individual bursts of muscle sympathetic nerve activity (MSNA), (10, 11, 34, 37). This approach is termed 'sympathetic-vascular transduction (SVT).' We will examine the hypothesis that SVT is exaggerated in obesity and insulin resistance and is attenuated by suppression of oxidative stress. Oxidative stress is the overabundance of reactive oxygen species and is another hallmark of hypertension, obesity, and insulin resistance. Oxidative stress can be safely reduced via intravenous infusion of ascorbic acid (Vit C) (4, 28). Therefore, we will use a randomized, double-blinded, placebo-controlled approach to test the hypothesis that elevated SVT will be attenuated by suppression of oxidative stress via ascorbic acid I.V. infusion compared with saline I.V. infusion (placebo) in obese adults with insulin resistance. Our study will identify a unique mechanism that can be targeted to reduce the excessively high prevalence of hypertension and risk for CVD in obesity and insulin resistance.