Acetate concentration correlates with MSNA in patients with resistant hypertension.

Purpose: Short-chain fatty acids (SCFAs), metabolites of colonic microflora fermentation of dietary fibre, have been implicated in experimental models and clinical trials to impact blood pressure (BP) regulation. Dietary interventions increasing serum SCFA levels have been associated with reduced 24-h systolic BP in hypertensive patients. However, the underlying mechanisms remain elusive. Given the role of the gut-brain axis and clear evidence for sympathetic nervous system activation as important modulators of blood pressure, we examined the relationship between sympathetic drive and SCFA concentration in patients with resistant hypertension (RH) and healthy control subjects (HC).

Methods: A total of 21 patients with RH (68.6 ± 9.7 years, 47% male) and 28 healthy control subjects (HC) (34.6 ± 16.7 years, 75% male) were recruited to undergo microneurography for determination of muscle sympathetic nerve activity (MSNA), automated office BP (AOBP) and blood collection for serum SCFA.

Results: Mean systolic AOBP was 156 ± 21 mmHg and 115 ± 10 mmHg for RH and HC, respectively (p < 0.0001). Serum acetate levels were 1340 ± 115.4 umol/L for HC and 724.5 ± 116.9 umol/L for RH (p < 0.0001). Butyrate and propionate concentrations did not significantly differ between groups. MSNA burst frequency was markedly elevated in RH compared with HCs (p < 0.001), with 25.3 ± 7.4 burst/minute in HC compared with 40.24 ± 8.3 burst/minute in RH. An inverse relationship was evident between serum acetate levels and MSNA burst frequency (p = 0.0267, R² = 0.4) along with increased sympathetic vascular transduction (p = 0.0008, R² = 0.82) in RH.

Conclusions: Our findings suggest that the beneficial effects of SCFA levels, in particular acetate, on cardiovascular regulation may at least in part be mediated by sympatho-inhibition and altered sympathetic vascular transduction.