Shawn Roberts, Abigail Stickford, Jonathon Stickford, Rachel Szeghy, Stephen Ratchford, Nina Stute, Marc Augenreich, Valesha Province. Appalachian State University, Boone, NC.

BACKGROUND: Otherwise healthy young adults recently infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have acutely elevated muscle sympathetic nerve activity (MSNA) compared with non-infected individuals. METHODS: Participants (n=9, 7M/2F, age 21.2±1.4 y) were tested three times following a positive SARS-CoV-2 polymerase chain reaction test (V1:47±15, V2:107±25, V3:170±19 days post-positive). Resting MSNA burst frequency, incidence, and total activity, heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure were measured at each visit. Data were collected for 5 min of supine rest. MSNA and HR were continuously measured and averaged over 5 min. Blood pressure was measured at the brachial artery at the first and fourth minute, then averaged. Sympathetic transduction to blood pressure was calculated as the absolute (mmHg) and relative (%) changes in mean arterial pressure (MAP) following a sympathetic burst and in response to sympathetic quiescence. RESULTS: Resting MSNA burst frequency (V1: 17±7, V2: 16±7, V3: 14±3 bursts∙min-1), incidence (V1: 31±12, V2: 28±13, V3: 25±4 bursts∙100 heart beats-1), and total activity (V1: 255±105, V2: 230±97, V3: 224±84 a.u.∙min-1) did not change across visits (p>0.05). SBP (V1: 135±11, V2: 127±8, V3: 121±11 mmHg, p=0.037) and DBP (V1: 77±7, V2: 71±7, V3: 67±6 mmHg, p=0.001) both decreased throughout recovery, while HR (V1: 57±9, V2: 60±6, V3: 57±8 bpm, p=0.163) did not change. The absolute (p=0.252) and relative (p=0.435) ΔMAP following an MSNA burst showed no significant changes over time Similarly, there were no changes in the absolute (p=0.169) or relative (p=0.127) ΔMAP following a non-bursting cardiac cycle. CONCLUSION: Despite cross-sectional data indicating elevated sympathetic activity following mild cases of COVID-19, longitudinal data suggests no change in sympathetic neural parameters over six months recovery. The diverging findings may indicate a) no effect of SARS-CoV-2 infection on sympathetic activity or, alternatively, b) prolonged recovery of autonomic function. However, the current results indicate clear reductions in DBP and SBP throughout six months of recovery from SARS-CoV-2. Given the lack of change in neural measures, changes in pressure are likely a result of other mechanisms.

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