Related Experiment Videos
Oxygen extraction in lamb skeletal muscle.
M B Hershenson1, P P O'Rourke, D A Christakis
1Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts.
Pediatric Research
|August 1, 1990
Summary
Neonatal lambs show reduced oxygen extraction during hypoxia due to suppressed metabolic rates, not impaired peripheral oxygen use. This suggests immature oxygen consumption is adaptable, not defective.
Area of Science:
- Physiology
- Neonatal Research
- Cardiovascular Science
Background:
- Previous studies indicate lower total-body oxygen extraction in 1-week-old lambs compared to older animals during hypoxia.
- This reduced extraction was hypothesized to stem from suppressed growth-related oxygen consumption (VO2) in various tissues, rather than a peripheral oxygen utilization defect.
Purpose of the Study:
- To investigate the oxygen extraction capacity of immature skeletal muscle in neonatal lambs.
- To differentiate between suppressed metabolic demand and intrinsic defects in peripheral oxygen use during hypoxia.
Main Methods:
- Isolated hind limb circulation model in 7- to 18-day-old lambs under stagnant hypoxia.
- Measurement of femoral arterial and venous blood gases, hemoglobin, O2 saturation, and blood flow.
- Calculation of hind limb oxygen delivery (DO2), extraction ratio, and VO2, with determination of critical DO2 levels.
Main Results:
- Hind limb VO2 remained independent of O2 supply until critically low DO2 levels were reached in most animals.
- Oxygen extraction during extreme hypoxia was submaximal, with ratios increasing significantly after administration of 2,4-dinitrophenol, an oxidative phosphorylation uncoupler.
Conclusions:
- The findings suggest that limitations in oxygen extraction in immature lambs are primarily due to the suspension of oxygen-consuming processes.
- These results indicate that the peripheral oxygen use capacity is not irreversibly impaired but rather adaptable to metabolic demands during early development.