Table 3.
Manipulation of peripheral chemoreceptor drive in Lowlanders at 344 m (LA)
| Lowlanders | |||||
|---|---|---|---|---|---|
| LA (n = 11) | AH (n = 11) | P value | LA + 100% O2 (n = 9) | P value† | |
| Haemodynamic variables | |||||
| S pO2 (%) | 98 ± 1 | 84 ± 4 | 0.001 | ||
| Heart rate (beats min−1) | 53 ± 10 | 68 ± 15 | 0.001 | 56 ± 11 | 0.55 |
| MAP (mmHg) | 84 ± 7 | 89 ± 5 | 0.05 | 88 ± 5 | 0.09 |
| Cardiac output (L min−1) | 5.1 ± 1.0* | 6.7 ± 1.8* | 0.002 | 5.7 ± 0.9 | 0.27 |
| Total peripheral resistance (mmHg L−1 min−1) | 16.8 ± 3.5* | 14.2 ± 3.7* | 0.01 | 15.9 ± 2.7 | 0.67 |
| MSNA | |||||
| Burst frequency (bursts min−1) | 11 ± 4 | 13 ± 6 | 0.43 | 11 ± 6 | 0.9 |
| Mean burst amplitude (a.u.) | 40 ± 7 | 52 ± 13 | 0.01 | 46 ± 14 | 0.06 |
| Total activity (a.u. min−1) | 502 ± 183 | 789 ± 489 | 0.06 | 549 ± 305 | 0.49 |
| Baroreflex function | |||||
| Vascular sympathetic baroreflex gain (% mmHg−1) | –2.7 ± 1.0 | –1.9 ± 0.6 | 0.02 | –2.3 ± 0.9 | 0.35 |
| Diastolic operating pressure (mmHg) | 67 ± 7 | 70 ± 4 | 0.09 | 70 ± 9 | 0.14 |
| Burst incidence operating point (bursts 100 HB−1) | 20 ± 6 | 19 ± 8 | 0.68 | 20 ± 9 | 0.77 |
| Cardiovagal baroreflex gain (ms mmHg−1) | 21.2 ± 8.4 | 23.5 ± 16.2 | 0.51 | 27.2 ± 17.4 | 0.24 |
| Systolic operating pressure (mmHg) | 117 ± 10 | 123 ± 7 | 0.12 | 121 ± 10 | 0.32 |
| RRI operating point (ms) | 1164 ± 226 | 933 ± 248 | 0.001 | 1177 ± 245 | 0.78 |
Data are presented as the mean ± SD. *Cardiac output and total peripheral resistance (n = 10). †Intragroup comparison for nine participants, LA vs. LA + 100% O2.