Firing patterns of muscle sympathetic neurons during apnea in chronic heart failure patients and healthy controls

In the present study we investigated the influence of end-expiratory breathing cessation on firing activity of muscle sympathetic fibers in 6 stable chronic heart failure (CHF) patients and in 6 healthy age and gender matched controls. Integrated multi-unit bursts, as well as action potentials (APs), were identified from multi-unit muscle sympathetic nerve activity (MSNA) recordings during baseline and during functional residual capacity (FRC) apnea. Compared with controls, CHF patients had higher burst frequency and AP firing frequency (P < 0.05) at baseline. FRC apnea caused an increase in the number of APs per multi-unit sympathetic burst, in the AP frequency (P < 0.05) and in the number of active clusters per multi-unit sympathetic burst in both groups (controls P < 0.06, CHF group P = 0.1). The data suggest a comparable pattern of sympathetic activation associated with breath hold in healthy middle-aged individuals and in stable CHF patients. Thus, recruitment patterns for this stress are not affected by CHF despite their elevated sympathetic state. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.