A pilot study on the association of the ergospirometric evaluation of gas metabolism and cellular oxygen metabolism measured by the Cellular Oxygen METabolism Monitor (COMET)
- Conditions
- healthy subjects
- Registration Number
- DRKS00016670
- Lead Sponsor
- WG Translational Septomics, Zentrum für Innovationskompetenz (ZIK) Septomics, Universitätklinikum Jena
- Brief Summary
Background: Mitochondria are the key players in aerobic energy generation via oxidative phosphorylation. Consequently, mitochondrial function has implications on physical performance in health and disease ranging from high performance sports to critical illness. The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) allows in vivo measurements of mitochondrial oxygen tension (mitoPO2). Hitherto, few data exist on the relation of mitochondrial oxygen metabolism and ergospirometry-derived variables during physical performance. This study investigates the association of mitochondrial oxygen metabolism with gas exchange and blood gas analysis variables assessed during cardiopulmonary exercise testing (CPET) in aerobic and anaerobic metabolic phases. Methods: Seventeen volunteers underwent an exhaustive CPET (graded multistage protocol, 50 W/5 min increase), of which 14 were included in the analysis. At baseline and for every load level PpIX-TSLT-derived mitoPO2 measurements were performed every 10 s with 1 intermediate dynamic measurement to obtain mitochondrial oxygen consumption and delivery (mitoVO2, mitoDO2). In addition, variables of gas exchange and capillary blood gas analyses were obtained to determine ventilatory and lactate thresholds (VT, LT). Metabolic phases were defined in relation to VT1 and VT2 (aerobic: <VT1, aerobic-anaerobic transition: =VT1 and <VT2 and anaerobic: =VT2). We used linear mixed models to compare variables of PpIX-TSLT between metabolic phases and to analyze their associations with variables of gas exchange and capillary blood gas analyses. Results: MitoPO2 increased from the aerobic to the aerobic-anaerobic phase followed by a subsequent decline. A mitoPO2 peak, termed mitochondrial threshold (MT), was observed in most subjects close to LT2. MitoDO2 increased during CPET, while no changes in mitoVO2 were observed. MitoPO2 was negatively associated with partial pressure of end-tidal oxygen and capillary partial pressure of oxygen and positively associated with partial pressure of end-tidal carbon dioxide and capillary partial pressure of carbon dioxide. MitoDO2 was associated with cardiovascular variables. We found no consistent association for mitoVO2. Conclusion: Our results indicate an association between pulmonary respiration and cutaneous mitoPO2 during physical exercise. The observed mitochondrial threshold, coinciding with the metabolic transition from an aerobic to an anaerobic state, might be of importance in critical care as well as in sports medicine.
- Detailed Description
Not available
Recruitment & Eligibility
- Status
- Complete
- Sex
- All
- Target Recruitment
- 17
written and informed consent
- suitability for exercise test (Physical Activity Readiness Questionnaire)
- significant pre-existing cardiological or pulmonal disease as well as significant diseases of the musculoskeletal system
-absolute contraindication for 5-aminolevulinic-acid-patch (required for COMET measurement: allergy to 5-aminolevulinic-acid-hydrocholride, acrylic adhesives, pigmented polyethylene or aluminized polyester, porphyria, skin disease which are caused or aggravated by sun light, increased sensitivity to sun light)
- allergy to Nonivamid or Nicoboxil (ingredients Finalgon®)
- pregnancy/breastfeeding
- participation in another intervention study
- previous participation in this study
Study & Design
- Study Type
- interventional
- Study Design
- Not specified
- Primary Outcome Measures
Name Time Method The primary aim is the evaluation of the association between mitochondrial oxygen consumption (mitoVO2) and the spiroergometrically measured oxygen uptake (VO2) over the time points T1 – T4.
- Secondary Outcome Measures
Name Time Method - Evaluation of the association between mitochondrial oxygen tension (mitoPO2) and the spiroergometrically measured oxygen uptake (VO2) over the time points T1 – T4.<br><br>- Evaluation of the association between mitochondrial oxygen delivery (mitoDO2) and the spiroergometrically measured oxygen uptake (VO2) over the time points T1 – T4.<br><br>- Corresponding analyses for mitoPO2, mitoVO2 and mitoDO2 and other variables from spiroergometry.<br><br>- Corresponding analyses for mitoPO2, mitoVO2 and mitoDO2 and variables from blood gas analysis.<br><br>- Characterisation of the course of mitoPO2, mitoVO2 and mitoDO2 between T1 – T4.<br><br>Additional research questions:<br>- Exploratory analysis on the influence of the maximum oxygen intake (VO2:max) on baseline values (T1) of mitoPO2, mitoVO2 and mitoDO2<br><br>- Activity induced differences in mitoPO2, mitoVO2 and mitoDO2 between T1 and the last load level during spiroergometry<br>