Effects of acute ketone monoester ingestion on heart rate, blood pressure and muscle sympathetic nerve activity at rest and stress in healthy adults

Exogenous ketone supplementation can impact cardiovascular regulation, but the effects on muscle sympathetic nerve activity (MSNA) remain unknown. In a randomized, crossover, double-blind design, 19 participants (23 ± 4 years.; female: n = 9) ingested an oral ketone monoester (KME; 0.4 g/kg) or isocaloric, isovolumetric placebo. Blood pressure, heart rate, brachial artery blood flow, and MSNA (microneurography; n = 14) were assessed at rest before and after ingestion and during two laboratory stressors: 2-min static handgrip exercise and 2-min of mental arithmetic. Capillary β-hydroxybutyrate increased 20 and 40 min post KME ingestion versus placebo (both, p < 0.001). Compared to placebo, KME had no effects on resting mean arterial pressure (Placebo: 78.3 ± 9.3 to 80.2 ± 10.5 mmHg; KME: 76.3 ± 8.3 to 79.5 ± 8.8 mmHg; interaction p = 0.32), heart rate (Placebo: 64.6 ± 12.3 to 69.6 ± 11.0 bpm; KME: 65.3 ± 10.6 to 72.6 ± 11.3 bpm; interaction p = 0.30), or MSNA burst frequency (Placebo: 17.7 ± 7.3 to 17.7 ± 6.7 bursts/minute; KME: 17.5 ± 6.1 to 18.2 ± 7.0 bursts/minute; interaction p = 0.72). Resting brachial artery blood flow and vascular conductance changed over time but did not differ between conditions (interactions, both p > 0.40). Neuro-cardiovascular responses during exercise (interactions, all p > 0.72) or mental stress (interactions, all p > 0.44) did not differ between conditions. Compared to placebo, acute KME ingestion did not modulate neuro-cardiovascular measures at rest or during stress in healthy young adults.