α-Adrenergic effects on low-frequency oscillations in blood pressure and R-R intervals during sympathetic activation
Bibliographic record
Abstract
The present study was designed to address the contribution of α-adrenergic modulation to the genesis of low-frequency (LF; 0.04-0.15 Hz) oscillations in R-R interval (RRi), blood pressure (BP) and muscle sympathetic nerve activity (MSNA) during different sympathetic stimuli. Blood pressure and RRi were measured continuously in 12 healthy subjects during 5 min periods each of lower body negative pressure (LBNP; -40 mmHg), static handgrip exercise (HG; 20% of maximal force) and postexercise forearm circulatory occlusion (PECO) with and without α-adrenergic blockade by phentolamine. Muscle sympathetic nerve activity was recorded in five subjects during LBNP and in six subjects during HG and PECO. Low-frequency powers and median frequencies of BP, RRi and MSNA were calculated from power spectra. Low-frequency power during LBNP was lower with phentolamine versus without for both BP and RRi oscillations (1.6 ± 0.6 versus 1.2 ± 0.7 ln mmHg(2), P = 0.049; and 6.9 ± 0.8 versus 5.4 ± 0.9 ln ms(2), P = 0.001, respectively). In contrast, the LBNP with phentolamine increased the power of high-frequency oscillations (0.15-0.4 Hz) in BP and MSNA (P < 0.01 for both), which was not observed during saline infusion. Phentolamine also blunted the increases in the LBNP-induced increase in frequency of LF oscillations in BP and RRi. Phentolamine decreased the LF power of RRi during HG (P = 0.015) but induced no other changes in LF powers or frequencies during HG. Phentolamine resulted in decreased frequency of LF oscillations in RRi (P = 0.004) during PECO, and a similar tendency was observed in BP and MSNA. The power of LF oscillation in MSNA did not change during any intervention. We conclude that α-adrenergic modulation contributes to LF oscillations in BP and RRi during baroreceptor unloading (LBNP) but not during static exercise. Also, α-adrenergic modulation partly explains the shift to a higher frequency of LF oscillations during baroreceptor unloading and muscle metaboreflex activation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".