Table 2.
Hemodynamic, sympathetic, renal vascular, and respiratory responses to IFRHG during Visit 3
| Base 1 | Base 2 | Base 2 + O2 | CA | IFRHG first 20 | IFRHG peak | PHGCA | Infusion | Time | Interaction | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MAP | mm Hg | Saline | 82 ± 2 | 86 ± 1 | 85 ± 2 | 85 ± 2 | 88 ± 2 | 114 ± 3 | 109 ± 3 | 0.876 | <0.001 | 0.676 |
| Ascorbic acid | 85 ± 2 | 86 ± 2 | 85 ± 2 | 85 ± 2 | 86 ± 3 | 115 ± 4 | 109 ± 2 | |||||
| HR | bpm | Saline | 59 ± 2 | 62 ± 3 | 60 ± 3 | 63 ± 4 | 66 ± 4 | 75 ± 3 | 60 ± 2 | 0.660 | <0.001 | 0.292 |
| Ascorbic acid | 59 ± 2 | 60 ± 3 | 58 ± 2 | 62 ± 3 | 67 ± 4 | 75 ± 3 | 62 ± 3 | |||||
| MSNA | burst/min | Saline | 24 ± 5 | 21 ± 4 | 20 ± 4 | 19 ± 4 | 25 ± 6 | 49 ± 3 | 43 ± 2 | 0.991 | <0.001 | 0.338 |
| Ascorbic acid | 24 ± 5 | 24 ± 5 | 22 ± 4 | 22 ± 3 | 26 ± 6 | 44 ± 6 | 39 ± 3 | |||||
| MSNA | total activity | Saline | 425 ± 71 | 367 ± 73 | 365 ± 76 | 341 ± 80 | 419 ± 101 | 1493 ± 199 | 1234 ± 127 | 0.880 | <0.001 | 0.991 |
| Ascorbic acid | 429 ± 76 | 429 ± 70 | 414 ± 68 | 345 ± 50 | 516 ± 163 | 1470 ± 340 | 1252 ± 283 | |||||
| RBV | cm/sec | Saline | 46.9 ± 3.6 | 47.0 ± 1.8 | 44.3 ± 4.6 | 47.8 ± 2.7 | 45.7 ± 6.2 | 50.8 ± 6.5 | 52.8 ± 4.3 | 0.150 | 0.872 | 0.634 |
| Ascorbic acid | 49.6 ± 2.2 | 48.0 ± 3.4 | 48.3 ± 3.4 | 51.4 ± 5.3 | 50.2 ± 5.5 | 48.6 ± 4.9 | 51.3 ± 6.0 | |||||
| SpO2 | % | Saline | – | 97.6 ± 0.2 | 99.4 ± 0.3 | – | – | 99.6 ± 0.3 | 99.6 ± 0.3 | 0.987 | <0.001 | 0.577 |
| Ascorbic acid | – | 97.6 ± 0.3 | 99.5 ± 0.2 | – | – | 99.4 ± 0.3 | 99.7 ± 0.3 | |||||
| EtCO2 | mm Hg | Saline | – | 43 ± 2 | 43 ± 2 | – | – | 42 ± 2 | 38 ± 2 | 0.134 | <0.001 | 0.543 |
| Ascorbic acid | – | 42 ± 2 | 41 ± 2 | – | – | 40 ± 2 | 36 ± 2 | |||||
| MV | L/min | Saline | – | 8.1 ± 1.0 | 8.9 ± 1.0 | – | – | 10.7 ± 1.3 | 11.6 ± 2.1 | 0.491 | 0.030 | 0.844 |
| Ascorbic acid | – | 8.5 ± 0.3 | 9.2 ± 0.8 | – | – | 12.1 ± 2.1 | 11.8 ± 2.0 |
Subjects (n = 9) underwent resting baseline periods before (Base 1) and after (Base 2) infusion of normal sterile saline and then ascorbic acid. Circulatory arrest (CA, inflation of upper arm cuff to suprasystolic pressure) occurred for 1 min prior to the onset of ischemic fatiguing rhythmic handgrip (IFRHG) exercise and the occlusion cuff remained inflated for 2 min of posthandgrip circulatory arrest (PHGCA). Measurements included beat-by-beat mean arterial pressure (MAP), heart rate (HR), muscle sympathetic nerve activity (MSNA), renal blood flow velocity (RBV), arterial oxygen saturation (SpO2), end tidal carbon dioxide (EtCO2), and minute ventilation (MV). Data are M ± SEM.