English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

This case study reports the efferent muscle sympathetic nerve activity (MSNA) discharge patterns during a sinus pause observed during a maximal end-expiratory apnea in a young healthy male (age = 26 yr). During a 15.3-s end-expiratory apnea following a bout of intermittent hypercapnic hypoxia, we observed a 5.2-s (R-R interval) sinus pause and integrated MSNA recording, demonstrating a square-wave discharge pattern atypical of sharp MSNA burst peaks entrained to cardiac cycles or during preventricular contractions. This abnormal MSNA discharge pattern was observed again during a follow-up experiment, where an end-expiratory apnea at baseline resulted in pronounced bradycardia (R-R intervals &gt;2.5-s) but failed to reproduce the 5.2-s sinus pause. Action potential (AP) discharge patterns during MSNA bursts were detected using a continuous wavelet transform approach. AP discharge increased by 300% during the end-expiratory apnea with 5.2-s sinus pause compared with baseline and involved increased firing (i.e., rate-coding) of AP clusters (bins of AP with similar morphology) already present during baseline and pronounced recruitment of larger-amplitude AP clusters not present at baseline. Large-amplitude AP clusters continued to discharge during sinus pause. In summary, we show MSNA discharge during sinus pause and pronounced bradycardia during end-expiratory apnea, which demonstrates a square-wave discharge with recruitment of latent larger-amplitude AP clusters. The MSNA discharge was terminated before systole following sinus pause potentially through an inhibitory influence of inspiration, or cardiac mechanoreceptor feedback causing burst termination. NEW &amp; NOTEWORTHY We characterize the occurrence of a square-wave discharge pattern of efferent muscle sympathetic nerve activity during a sinus pause in a young healthy male. This discharge pattern comprised large recruited action potential clusters undetected at baseline that continuously discharged during the sinus pause. Notably, this discharge pattern was still contained within a single cardiac cycle.

Case Studies in Physiology: Sympathetic neural discharge patterns in a healthy young male during end-expiratory breath hold-induced sinus pause