An oral glutamine load enhances renal acid secretion and function

Area of Science:

• Nephrology
• Physiology
• Biochemistry

Background:

• Oral glutamine has been shown to increase plasma bicarbonate concentrations in healthy adults.
• The specific renal mechanisms responsible for this base-generating response remain to be fully elucidated.

Purpose of the Study:

• To investigate the renal mechanisms underlying the base-generating response to L-glutamine.
• To determine if L-glutamine directly contributes to bicarbonate generation or indirectly influences renal acid-base regulation.

Main Methods:

• Healthy adults ingested either a vehicle (diet soda) or vehicle plus L-glutamine.
• Researchers compared the gain in extracellular fluid bicarbonate with renal acid elimination (ammonium excretion and tubular acid secretion).
• Glomerular filtration rate and acid-base parameters were monitored over 90 minutes.

Main Results:

• L-glutamine ingestion significantly increased plasma bicarbonate concentration and extracellular fluid bicarbonate.
• Ammonium excretion accounted for less than 2% of the newly generated bicarbonate.
• Renal acid secretion, including net acid excretion and enhanced bicarbonate reabsorption, accounted for the observed base gain.
• Oral glutamine increased glomerular filtration rate.

Conclusions:

• L-glutamine does not act as a direct precursor for bicarbonate.
• The base-generating effect of L-glutamine is mediated indirectly by accelerating renal acid secretion.
• This acceleration of acid secretion appears to be coupled with an increased glomerular filtration rate.