查看文章

This study investigated the influence of ventilation on sympathetic action potential (AP) discharge patterns during varying levels of high chemoreflex stress. In seven trained breath-hold divers (age 33 ± 12 yr), we measured muscle sympathetic nerve activity (MSNA) at baseline, during preparatory rebreathing (RBR), and during 1) functional residual capacity apnea (FRC_Apnea) and 2) continued RBR. Data from RBR were analyzed at matched (i.e., to FRC_Apnea) hemoglobin saturation (HbSat) levels (RBR_Matched) or more severe levels (RBR_End). A third protocol compared alternating periods (30 s) of FRC and RBR (FRC-RBR_ALT). Subjects continued each protocol until 85% volitional tolerance. AP patterns in MSNA (i.e., providing the true neural content of each sympathetic burst) were studied using wavelet-based methodology. First, for similar levels of chemoreflex stress (both HbSat: 71 ± 6%; P = NS), RBR …