Free amino acids in plasma and muscle during 24 hours post-operatively--a descriptive study

Area of Science:

• Biochemistry
• Surgical Metabolism
• Nutritional Science

Background:

• Intracellular amino acid patterns in skeletal muscle are known on day 3 post-surgery.
• The early temporal changes in muscle amino acids during the first 24 hours post-surgery are not well understood.

Purpose of the Study:

• To investigate the temporal changes in skeletal muscle and plasma amino acid concentrations during the first 24 hours after elective abdominal surgery.
• To compare early post-operative muscle amino acid alterations with those observed later and with plasma level changes.

Main Methods:

• Analysis of skeletal muscle and plasma amino acid concentrations in 14 patients undergoing elective abdominal surgery.
• Measurements were taken pre-operatively, and at 12 and 24 hours post-operatively.

Main Results:

• Skeletal muscle glutamine and basic amino acids decreased significantly within 24 hours.
• Essential amino acids initially decreased then partially recovered, while branched-chain amino acids (BCAA) showed a similar pattern, increasing by 24 hours.
• Muscle alanine concentration increased significantly, while plasma alanine increased at 12 hours, with most other plasma amino acids normalizing by 24 hours, except phenylalanine.
• Early muscle amino acid changes were consistent with later observed patterns, but plasma changes only partially reflected muscle alterations.

Conclusions:

• Skeletal muscle amino acid concentrations undergo significant dynamic changes within the first 24 hours post-surgery.
• These early muscle changes foreshadow the patterns seen later, highlighting the importance of early metabolic monitoring.
• Plasma amino acid concentrations do not fully mirror the complex intracellular shifts in skeletal muscle during the early post-operative period.