Post-exercise hypotension and skeletal muscle oxygenation is regulated by nitrate-reducing activity of oral bacteria

• Published in: Free radical biology & medicine 2019-11, Vol.143, p.252-259
• Main Authors: Cutler, C., Kiernan, M., Willis, J.R., Gallardo-Alfaro, L., Casas-Agustench, P., White, D., Hickson, M., Gabaldon, T., Bescos, R.
• Format: Article
• Language: English
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2019.07.035

Post-exercise hypotension (PEH) is a common physiological phenomenon leading to lower blood pressure after acute exercise, but it is not fully understood how this intriguing response occurs. This study investigated whether the nitrate-reducing activity of oral bacteria is a key mechanism to trigger PEH. Following a randomized, double blind and crossover design, twenty-three healthy individuals (15 males/8 females) completed two treadmill trials at moderate intensity. After exercise, participants rinsed their mouth with antibacterial mouthwash to inhibit the activity of oral bacteria or a placebo mouthwash. Blood pressure was measured before, 1h and 2 h after exercise. The microvascular response to a reactive hyperaemia test, as well as blood and salivary samples were taken before and 2 h after exercise to analyse nitrate and nitrite concentrations and the oral microbiome. As expected, systolic blood pressure (SBP) was lower (1 h: -5.2 ± 1.0 mmHg; P  0.05), and impaired microvascular response (peak TOI baseline: 85.1 ± 3.1%; peak TOI post-exercise: 84.6 ± 3.2%; P > 0.05). Diversity of oral bacteria did not change after exercise in any treatment. These findings show that nitrite synthesis by oral commensal bacteria is a key mechanism to induce the vascular response to exercise over the first period of recovery thereby promoting lower blood pressure and greater muscle oxygenation. [Display omitted]