Table 1.
MSNA and hemodynamic measurements at baseline and during LBNP and recovery
| LBNP, Torr |
|||||||
|---|---|---|---|---|---|---|---|
| Baseline | −10 | −20 | −30 | −40 | Recovery | ANOVA (F ratio; P value) | |
| MSNA burst frequency, bursts/min | 8.0 ± 2.1 | 13.2 ± 2.7 | 16.8 ± 2.7* | 22.0 ± 3.1* | 28.5 ± 4.0* | 7.6 ± 3.0 | 25.0;<0.0001 |
| MSNA bursts incidence, bursts/100 heartbeats | 14.8 ± 4.1 | 24.4 ± 5.2* | 30.2 ± 5.3* | 37.3 ± 6.1* | 42.3 ± 6.7* | 13.5 ± 5.1 | 16.4;<0.0001 |
| Heart rate, beats/min | 57 ± 3 | 55 ± 2 | 57 ± 2 | 61 ± 2* | 68 ± 3* | 57 ± 2 | 23.9;<0.0001 |
| SBP, mmHg | 125 ± 2 | 130 ± 2* | 128 ± 3 | 124 ± 3 | 121 ± 4 | 130 ± 3* | 5.6;<0.0001 |
| DBP, mmHg | 72 ± 1 | 72 ± 2 | 73 ± 2 | 73 ± 2 | 74 ± 2 | 73 ± 2 | 0.7;0.618 |
| BA diameter, mm | 4.03 ± 0.16 | 3.97 ± 0.14 | 3.97 ± 0.14 | 3.98 ± 0.15 | 3.97 ± 0.15 | 3.98 ± 0.15 | 1.5;0.190 |
| BA mean blood velocity, cm/s | 3.3 ± 0.3 | 2.0 ± 0.1* | 1.9 ± 0.1* | 1.9 ± 0.2* | 2.0 ± 0.1* | 3.1 ± 0.3 | 17.5;<0.0001 |
| BA antegrade velocity, cm/s | 3.7 ± 0.3 | 2.5 ± 0.1* | 2.5 ± 0.1* | 2.6 ± 0.1* | 2.8 ± 0.1* | 3.5 ± 0.2 | 15.0;<0.0001 |
| BA retrograde velocity, cm/s | 0.39 ± 0.12 | 0.52 ± 0.12* | 0.56 ± 0.12* | 0.67 ± 0.14* | 0.79 ± 0.16* | 0.40 ± 0.13 | 12.4;<0.0001 |
Values are means ± SE. MSNA, muscle sympathetic nerve activity; LBNP, lower body negative pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure; BA, brachial artery.
*
Significantly different from baseline.