The role of skeletal muscle and liver on lactate metabolism during hypoxia in rats.
OBJECTIVE
This study was planned to investigate whether the skeletal muscle and liver produce or consume lactate under hypoxic conditions.


METHODS
Wister rats were anesthetized and mechanically ventilated. Microdialysis probes were inserted into the rat skeletal muscle and liver, and arterial cannulation was performed. Hypoxia was induced for 30 min by the inhalation of 10% oxygen in nitrogen. Interstitial lactate concentrations in the skeletal muscle and liver were measured using an in vivo microdialysis method before, during, and after hypoxic hypoxia. The blood lactate concentration, mean arterial blood pressure, and blood gas were also measured.


RESULTS
Before hypoxia, there was no significant difference among the blood lactate concentration and interstitial lactate concentrations of the skeletal muscle and liver. During hypoxia, arterial oxygen tension decreased to 34.2 +/- 1.3 mmHg, and the lactate concentrations in these tissues increased significantly in comparison to the control values. However, the lactate concentrations in the skeletal muscle and liver interstitium were significantly lower than that in the blood, with the peak lactate concentration in the skeletal muscle interstitium being only one-third of that in the blood. After correction of hypoxia, the blood lactate concentration decreased to levels comparable to the skeletal muscle and liver interstitial lactate concentrations.


CONCLUSIONS
It is suggested that the skeletal muscle as well as the liver may consume lactate under hypoxic hypoxia.
Fuse
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Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.