Abstract
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.