Effects of dietary nitrates on systemic and cerebrovascular hemodynamics

Abstract

Cerebral blood flow dysregulation is often associated with hypertension. We hypothesized that a beetroot juice (BRJ) treatment could decrease blood pressure and cerebrovascular resistance (CVR). We subjected 12 healthy females to control and BRJ treatments. Cerebrovascular resistance index (CVRI), systolic blood pressure (SBP), total vascular resistance (TVR), and the heart rate-systolic pressure product (RPP) measured at rest and at two exercise workloads were lower after the BRJ treatment. CVRI, SBP, and RPP were lower without a lower TVR at the highest exercise level. These findings suggest improved systemic and cerebral hemodynamics that could translate into a dietary treatment for hypertension.

Figure 1

Effects of beetroot juice treatment on middle cerebral arterial blood flow velocity. Bars represent means ± standard errors for middle cerebral artery mean blood flow velocity, expressed in cm·s⁻¹. The study subjects were 12 healthy, normotensive young adult African-American females. Left panel: placebo control orange juice treatment. Right panel: beetroot juice treatment. *Difference between control and beetroot juice treatments statistically significant at P < 0.05.

Figure 2

Effects of beetroot juice treatment on middle cerebral arterial cerebrovascular resistance index. Bars represent means ± standard errors for middle cerebrovascular resistance index, computed as the ratio mean arterial blood pressure/mean middle cerebral artery blood flow velocity, expressed in mm Hg·cm⁻¹·s⁻¹. The study subjects were 12 healthy, normotensive young adult African-American females. Left panel: placebo control orange juice treatment. Right panel: beetroot juice treatment. *Difference between control and beetroot juice treatments statistically significant at P < 0.05.

Figure 3

Effects of beetroot juice treatment on total vascular resistance. Bars represent means ± standard errors for total vascular (peripheral) resistance computed as the ratio mean arterial blood pressure/cardiac output, expressed in dyne·s·cm⁻⁵. The subjects were 12 healthy, normotensive young adult African-American females. Left panel: placebo control orange juice treatment. Right panel: beetroot juice treatment. *Difference between control and beetroot juice treatments statistically significant at P < 0.05.