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Updated: Jul 31, 2026
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Methods for the Determination of Rates of Glucose and Fatty Acid Oxidation in the Isolated Working Rat Heart
Published on: September 28, 2016
Fatty acid cycling in the fasting rat
B Kalderon1, N Mayorek, E Berry
1Department of Human Nutrition and Metabolism, Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel.
Summary
In fasted rats, adipose tissue lipolysis is largely futile, with most released fatty acids reesterified. This futile fatty acid cycling allows fine-tuning of energy metabolism to meet metabolic demands.
Area of Science:
- Metabolic regulation
- Adipose tissue physiology
- Fatty acid metabolism
Background:
- Adipose tissue plays a crucial role in regulating energy balance through lipolysis and reesterification.
- Understanding fatty acid flux is essential for comprehending metabolic states like fasting and calorigenesis.
Purpose of the Study:
- To investigate adipose tissue lipolysis and fatty acid reesterification in rats under basal and calorigenic conditions.
- To elucidate the fate of free fatty acids (FFA) released during fasting and their regulation.
Main Methods:
- Rats were fasted for 15 hours.
- Metabolic conditions were induced using thyroid hormone and Medica 16.
- Quantification of fatty acid flux, lipolysis, reesterification, and oxidation was performed.
Main Results:
- Fasted rats exhibit significant futile cycling of fatty acids, with 57% of lipolyzed FFA reesterified within adipose tissue.
- FFA reesterification occurs both intracellularly and via plasma FFA uptake by adipose tissue.
- Calorigenesis increases FFA oxidation and adipose lipolysis, while hepatic reesterification remains negligible.
Conclusions:
- Adipose tissue acts as both a source and sink for fatty acids, regulating total body fatty acid metabolism.
- The futile nature of fatty acid cycling provides a mechanism for fine-tuning energy metabolism.
- This metabolic regulation is critical for adapting to changing energy demands.
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