Adverse Neurogenic Actions of Dietary Salt

Excess dietary salt causes target organ damage and increases the risk for adverse cardiovascular (CV) events independent of blood pressure (BP). Recent data in salt-resistant, normotensive rodents suggest that high dietary salt enhances the excitability or gain of sympathetic circuits, exaggerates sympathetic and CV responses to various stimuli, and increases BP variability (BPV). There are limited data regarding the impact of dietary salt intake on sympathetic nerve activity (SNA) and CV function in salt-resistant humans as well as the underlying mechanisms contributing to these adverse effects. The long-term goal is to determine how dietary salt adversely affects BP regulation and CV health. The objective of this proposal is to comprehensively evaluate the impact of dietary salt intake on SNA and CV reactivity and BPV in normotensive humans. The investigators have 2 specific aims: 1) Aim 1 will test the hypothesis that high dietary salt increases SNA and CV reactivity in normotensive adults, 2) Aim 2 will test the hypothesis that high dietary salt increases BPV in normotensive adults. The expected outcome is to demonstrate that dietary salt loading increases CV reactivity and BPV through a sympathetic nervous system mechanism that originates in the brain. The proposed research is significant, as these studies will provide empirical evidence that dietary salt intake impacts neurohumoral control of the circulation in salt-resistant humans. The proposed research is innovative because it will identify a novel neurogenic action of dietary salt in human CV regulation.