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. 2012 Apr 26;3:110. doi: 10.3389/fphys.2012.00110

Figure 5.

Figure 5

Arterial pressure (AP) and muscle sympathetic nerve activity (MSNA) for three representative subjects 2 min before the onset of presyncope. The lowest arterial pressure (BP) recorded for each subject is shown in the upper right corner of each AP panel. In subject A185, MSNA decreased in the last 2 min of LBNP (−120 to −60 s, 82 bursts/min; −60 s to presyncope, 64 bursts/min), but was still maintained at high levels relative to the pre-LBNP control (36 bursts/min). Subject A075 displayed burst fusion, elevated MSNA over control (25 bursts/min), and no withdrawal of MSNA at presyncope (−120 to −60 s, 53 bursts/min; −60 s to presyncope, 54 bursts/min). Subject A199 (a low tolerant subject) did not display large increases in MSNA from the pre-LBNP control value (17 bursts/min) and also did not demonstrate MSNA withdrawal at presyncope (−120 to −60 s, 22 bursts/min; −60 s to presyncope, 21 bursts/min). From Cooke et al. (2009).