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. 2019 Apr 7;597(9):2379–2390. doi: 10.1113/JP277663

Figure 3. Cardiovagal baroreflex function.

Figure 3

Group average regressions between RRI and SBP in Lowlanders (n = 10) at 344 m (LA) and 5050 m (HA) and in native Sherpa at HA (n = 7). The operating points are indicated by symbols and error bars (mean ± SD). RRI significantly decreased in Lowlanders at HA, relative to Lowlanders at LA, although it was similar in Sherpa relative to Lowlanders at HA. Operating SBP were similar. This indicated a downward (RRI) resetting of the cardiovagal baroreflex in Lowlanders following ascent to HA. The slope of the relationship was less steep in Lowlanders at HA (16.2 ± 8.2 ms mmHg−1) vs. LA (20.6 ± 5.0 ms mmHg−1; P = 0.007), indicating a reduction in cardiovagal baroreflex gain following ascent to HA in Lowlanders. The slope of the relationship between SBP and RRI was similar in Sherpa at HA (12.9 ± 5.4 ms mmHg−1; P = 0.60) relative to Lowlanders at HA, indicating no differences in reflex gain. Compared to Lowlanders at LA, operating SBP was similar but RRI was significantly smaller in Sherpa at HA, and the slope of the relationship was less steep (P = 0.01) [Color figure can be viewed at wileyonlinelibrary.com]