Slow deep breathing augmented MSNA transduction, with greater increases in MAP (+6.0 vs +3.0 mmHg, P<0.001) and greater decreases in SFA flow (-9.8 vs -6.3 ml/min, P=0.002) following MSNA bursts.
Observational (n=12)
Does slow deep breathing alter the dynamic transduction of sympathetic nerve activity to peripheral blood flow and blood pressure in healthy volunteers?
Slow deep breathing reduces overall muscle sympathetic nerve activity but augments its transduction to blood pressure and peripheral blood flow, potentially facilitating venous return.
Absolute Event Rate: 6% vs 3%
p-value: p=<0.001
The effect of slow deep breathing (SDB) on the dynamic transduction of sympathetic nerve activity to the superficial femoral artery (SFA), femoral vein (FV) and blood pressure was determined. In twelve healthy volunteers (5 women, 25±7 years, mean±SD) simultaneous imaging of the SFA and FV, along with contemporary measures of muscle sympathetic nerve activity (MSNA), were obtained and signal-averaging techniques used to quantify sympathetic neurovascular transduction at rest (baseline) and during 5 min SDB at 6 breaths/min. At baseline, MSNA bursts were followed by transient increases in mean arterial pressure (MAP; peak +3.0±1.2 mmHg), decreases in SFA flow (nadir -6.3±4.5 ml/min), and small, inconsistent increases in FV flow (peak +4.3±6.7 ml/min). SDB decreased MSNA burst frequency and burst incidence by ~30% while MAP was unchanged. During SDB, MSNA bursts were followed by greater increases in MAP (peak +6.0±2.4 mmHg, P<0.001 vs. baseline), greater decreases in SFA flow (nadir -9.8±4.0 ml/min, P=0.002 vs. baseline), and a tendency for a greater increase in FV flow (peak +20.6±21.0 ml/min, P=0.051). Therefore, while SDB reduces MSNA, the augmented MSNA transduction to blood pressure may help to preserve MAP. SDB evoked greater reductions in SFA flow and increases in FV flow following a MSNA burst, which may work synergistically with the respiratory muscle pump to facilitate venous return. Collectively, these findings highlight the important role played by MSNA in the dynamic regulation of peripheral blood flow, venous return and blood pressure.
Nardone et al. (Tue,) conducted a observational in healthy volunteers (n=12). slow deep breathing (SDB) vs. rest (baseline) was evaluated on peak increase in mean arterial pressure following MSNA bursts (mmHg) (p=<0.001). Slow deep breathing augmented MSNA transduction, with greater increases in MAP (+6.0 vs +3.0 mmHg, P<0.001) and greater decreases in SFA flow (-9.8 vs -6.3 ml/min, P=0.002) following MSNA bursts.