Abstract
Sympathetic nerve activity (SNA) is important for beat‐to‐beat regulation of arterial blood pressure (BP). Previous studies have indicated that a burst of muscle SNA results in a peak BP response of ~3 mmHg with a latency of 5.5 seconds. This delay is thought to represent the transduction time of a SNA burst into a change in vascular smooth muscle tone. However, the influence of a SNA burst on beat‐to‐beat alterations in vascular conductance has not been clearly identified. Therefore, in 5 young men, muscle SNA, diastolic BP and brachial artery blood flow were measured. Changes in diastolic BP and calculated forearm vascular conductance (FVC) were characterized for 15 cardiac cycles following each individual muscle SNA burst to describe the latency and magnitude of peak changes in diastolic BP and FVC to the burst of muscle SNA. A clear increase in DBP (Δ 2.0±0.2 mmHg) followed a burst of muscle SNA with a latency of 5.9±0.7 seconds. In contrast, decreases in FVC after a burst of muscle SNA were not readily apparent. These preliminary results suggest that a clear magnitude and latency for increases in diastolic BP following a burst of muscle SNA can be identified on a beat to beat basis; however, related decreases in FVC are not easily observed. The pattern of muscle SNA firing (single burst vs. volley of bursts) and burst size warrants additional consideration. Support: NIH RO1HL093167
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