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Metabolic substrate utilization by rabbit proximal tubule. An NADH fluorescence study
1Department of Physiology, Duke University, Durham, North Carolina 27710.
The American Journal of Physiology
|March 1, 1988
Summary
Short-chain fatty acids, carboxylic acids, and amino acids significantly impact kidney cell metabolism. Short-chain fatty acids show the highest effectiveness and affinity in boosting NADH fluorescence and oxygen consumption (QO2).
Area of Science:
- Biochemistry
- Renal Physiology
- Cellular Metabolism
Background:
- Cellular metabolism in renal proximal tubules is crucial for kidney function.
- Understanding substrate utilization is key to comprehending renal energy production.
Purpose of the Study:
- To investigate the impact of various metabolic substrates on NADH fluorescence and oxygen consumption in rabbit proximal tubule suspensions.
- To determine the relative affinities of different substrates for influencing cellular redox state.
Main Methods:
- Rabbit proximal tubule suspensions were utilized.
- NADH fluorescence and oxygen consumption (QO2) were measured.
- The effects of short-chain fatty acids, carboxylic acids, and amino acids were assessed.
Main Results:
- Short-chain fatty acids were the most potent substrates, increasing both NADH fluorescence and QO2.
- A proportional increase in QO2 with NADH fluorescence was observed for all tested substrates.
- Short-chain fatty acids exhibited the highest affinity (10 microM range), followed by carboxylic acids (100 microM range).
Conclusions:
- The primary mechanism by which these substrates enhance QO2 is by increasing reducing equivalents delivery to NAD.
- Renal cortical cell metabolic rate and NADH redox state are highly sensitive to the type of available metabolic substrate.
- These findings provide insights into substrate-dependent regulation of kidney cell metabolism.