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Monocarboxylate-uptake kinetics in perfused rat heart
Advances in Myocardiology
|January 1, 1985
Summary
This study reveals that lactate and pyruvate transport across cell membranes is facilitated by a specific carrier protein, not simple diffusion. This finding is crucial for understanding cellular energy metabolism.
Area of Science:
- Cellular Physiology
- Biochemistry
- Cardiovascular Research
Background:
- Lactate and pyruvate transport across cell membranes are critical for cellular energy metabolism.
- The precise mechanisms governing sarcolemmal monocarboxylate transport remain largely unknown.
Purpose of the Study:
- To investigate the kinetics of pyruvate and lactate uptake into rat hearts.
- To determine if sarcolemmal monocarboxylate transport is mediated by a specific carrier protein.
Main Methods:
- Aerobically perfused rat hearts were used, depleted of intracellular substrates.
- Transient infusion of radiolabeled lactate or pyruvate with [3H]mannitol to measure uptake.
- Computer optimization analysis of uptake rates to identify transport kinetics.
Main Results:
- Monocarboxylate transport exhibited saturation kinetics, not simple diffusion.
- Observed cross-inhibition between lactate and pyruvate uptake.
- Identified a high-affinity lactate and low-affinity pyruvate translocase.
Conclusions:
- Sarcolemmal monocarboxylate transport is mediated by a specific carrier protein.
- This carrier exhibits distinct affinities for lactate and pyruvate.
- The findings provide insight into the regulation of cellular energy substrate transport.