Yoga Postures and Slow Deep Breathing in Altering Mechanistic Outcomes in Hypertension

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Project Summary Hypertension is a pervasive disease with rising mortality rates in the U.S. Although complex, hypertension pathophysiology entails disruptions in vascular homeostasis driven by increased immune cell reactive oxygen species and subsequent oxidative stress. Yoga's blood pressure-lowering effects have been elucidated; however, the mechanisms are unknown. Our studies have found significant enhancements in flow-mediated dilation, a nitric oxide dependent measure of vascular health, following yoga interventions. As oxidative stress leads to reductions in nitric oxide bioavailability, it is possible that reductions in reactive oxygen species and improvements in redox homeostasis represent a biological mechanism by which yoga improves vascular function. Markers of oxidative stress have improved with yoga; however, immune cells, which are key sources of reactive oxygen species in hypertension, have not been investigated in prior yoga studies. NADPH oxidase expediates disease progression in hypertension via enhanced reactive oxygen species scavenging of nitric oxide, compromised endothelium-dependent vasodilation, and resultant increases in total peripheral resistance. While NADPH oxidase has declined following aerobic exercise interventions, this key enzyme has never been explored in yoga research. The proposed study will investigate immune cell reactive oxygen species and NADPH oxidase as biological mechanisms accounting for yoga's vascular and hemodynamic effects in unmedicated adults with elevated blood pressure or stage I hypertension (Aim 1). In response to 12-week yoga interventions, we will explore reactive oxygen species and NADPH oxidase in peripheral blood mononuclear cells as primary and protein carbonylation, a consequence of oxidative stress, and superoxide dismutase, a marker of antioxidant capacity, as exploratory outcomes. We will also establish a timeline of alterations in molecular, vascular, and hemodynamic outcomes by incorporating measurements at 4-week intervals. We hypothesize that oxidative stress markers will improve in response to the yoga intervention and these changes will be associated with reductions in blood pressure and enhanced endothelial function. As yoga is a composite of postures and slow, deep breathing practices, we will also delineate the contribution of slow deep breathing in modulating these mechanistic outcomes (Sub-Aim 1). Slow, deep breathing alone has resulted in favorable alterations in blood pressure and vascular function. We therefore postulate that slow deep breathing alone will be as effective as yoga in improving BP-related mechanistic outcomes. This study serves as an initial step in the PI's long-term goal of delineating mechanisms by which yoga could lower the risk of or serve as a therapeutic intervention for cardiovascular diseases. This research is significant in that it could establish the role of the immune system in altering clinical outcomes with yoga in hypertensive adults. As oxidative stress also plays a role in other diseases marked by disruptions in vascular homeostasis, results could unveil a mechanism by which yoga could ameliorate other conditions as well.