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Hydroxymalonate inhibits lactate uptake by the rabbit hindlimb
G Gutierrez1, E Fernandez, F J Hurtado
1Pulmonary and Critical Care Medicine Division, University of Texas Health Science Center at Houston 77030.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 1, 1994
Summary
Skeletal muscles take up lactate during hypoxia. The malic reaction is crucial for this lactate metabolism in resting muscles, as shown by hydroxymalonate inhibiting lactate uptake in rabbits.
Area of Science:
- Exercise Physiology
- Skeletal Muscle Metabolism
- Biochemistry
Background:
- Skeletal muscle lactate uptake is vital during conditions like hypoxia and exercise.
- The malic reaction, converting pyruvate to malate, is a potential metabolic pathway for lactate in resting muscle.
Purpose of the Study:
- To investigate the role of the malic reaction in skeletal muscle lactate metabolism.
- To determine if inhibiting the malic reaction affects lactate uptake in resting rabbit hindlimbs during hypoxemia.
Main Methods:
- Mechanically ventilated rabbits underwent sequential periods of normoxia, hypoxemia, and reoxygenation.
- Hindlimb lactate uptake was measured using arteriovenous lactate differences and femoral blood flow.
- Rabbits received intravenous hydroxymalonate (malic reaction inhibitor) or saline control.
Main Results:
- Hypoxemia reduced hindlimb oxygen transport but not oxygen consumption.
- Control rabbits showed net hindlimb lactate uptake during hypoxemia (4.5 ± 0.9 μmol/min).
- Hydroxymalonate-treated rabbits exhibited net lactate release (-0.5 ± 1.0 μmol/min), indicating inhibited uptake.
Conclusions:
- The malic reaction significantly contributes to lactate metabolism in resting skeletal muscle.
- Inhibition of the malic reaction reverses net lactate flux, supporting its role in lactate uptake.
- This study highlights the importance of the malic reaction in managing lactate during hypoxic conditions in skeletal muscle.