Cardiovascular and Hematological Responses to Simulated Dynamic Apnea in Breath Hold Divers
Notice bibliographique
Résumé
The mammalian dive reflex, characterized by bradycardia and peripheral vasoconstriction, occurs in all mammals, including humans, in response to apnea or facial submersion in water. However, the dive reflex to a single, maximal effort dynamic apnea (DYN), and how it compares to a time-matched exercise control trial (EX), has not been studied. We examined the hypotheses that, when compared to EX, (a) the magnitude of the cardiovascular response, including reduced heart rate (HR), increased systolic-, diastolic-, and mean arterial- pressure (SBP, DBP, and MAP, respectively) would be greater during DYN, and; (b) red blood cells (RBCs), hemoglobin (Hb), and hematocrit (Hct) would also all be elevated following DYN. Twenty-three (F=6) apnea divers performed a maximal DYN and time-matched EX on a swimming ergometer without facial submersion. For the DYN protocol, participants were instructed to exercise maximally while holding their breath which the EX trial was then time and distance matched. Trial duration was similar between DYN (126±7s [mean±SE]) and EX (126±7s;P>0.3), however the change in venous lactate (DYN 1.8±0.3mmol/l, EX: 0.2±0.2mmol/l) and peripheral oxygen saturation (DYN: -15±3%, EX: -1.8±0.5%;p<0.05, both comparisons) were greater during DYN compared to EX. During DYN ΔSBP (DYN: 107±6mmHg, EX: 45±6 mmHg), ΔDBP (DYN: 46±3mmHg, EX: 17±3mmHg) and ΔMAP (DYN: 66±3mmHg EX: 26±3mmHg) were increased compared to EX, while ΔHR was greater during EX (DYN: -24±5bpm, EX: 36±5bpm;p<0.0001, all comparisons). Similarly, the change in estimated stroke volume was further reduced in DYN (DYN: -15.2±3.3mL, EX: -1.0±3.3m;p<0.005) while Δcardiac output was reduced during DYN (-2.9±0.4l/min) and elevated during EX (2.9±0.4l/min;p<0.0001). The change in RBCs (DYN: 0.20±0.04x10 6 cells/μL, EX: 0.06±0.04x10 6 cells/μL) and Hct (DYN:1.7±0.3%, EX:0.5±0.3%) were greater during DYN than EX (p<0.02, both comparisons), whereas ΔHb (DYN: 4.0±0.9g/dL, EX: 1.9±0.8g/dL) and spleen volume (DYN: -9.1±7.4cm 3 , EX:-8.3±6.4cm 3 ;P>0.1, both comparisons) was comparable between the two trials. There was a main effect of sex for ΔDBP (Female: 36±3mmHg, Male: 27±2mmHg), and ΔMAP (Female: 52±5mmHg, Male: 40±3mmHg) indicating that females overall had a greater blood pressure response to both DYN and EX (p<0.05, both comparisons). Together, these data indicate that DYN elicits a greater cardiovascular and hematological response than EX alone, likely due to the combined activation of the metabo- and chemo-reflex during DYN. The mechanism(s) that may elicit greater changes in blood pressure response to DYN and EX in females when compared to males warrant future investigation. NSERC, University Research Chair. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».