TEN AMINO ACIDS ESSENTIAL FOR PLASMA PROTEIN PRODUCTION EFFECTIVE ORALLY OR INTRAVENOUSLY.

Area of Science:

• Biochemistry
• Physiology
• Nutritional Science

Background:

• Plasmapheresis in dogs leads to hypoproteinemia and constant plasma protein production with controlled protein intake.
• Protein-depleted dogs exhibit normal outward appearance but reduced resistance to infection and intoxication.
• Dietary protein is crucial for maintaining physiological balance and immune function.

Purpose of the Study:

• To investigate the efficacy of a crystalline amino acid mixture (Rose) in maintaining plasma protein production in protein-depleted dogs.
• To assess the role of specific amino acids in protein synthesis, nitrogen balance, and overall physiological stability.
• To evaluate the potential of amino acid solutions for intravenous administration in therapeutic settings.

Main Methods:

• Dogs underwent plasmapheresis to induce controlled hypoproteinemia.
• Dietary protein was replaced with a specific mixture of ten crystalline amino acids (Rose mixture).
• Amino acid composition of the diet was systematically altered by omitting specific amino acids or substituting methionine with cystine.
• Plasma protein production, body weight, and nitrogen balance were monitored.

Main Results:

• The crystalline amino acid mixture effectively supported plasma protein production, weight maintenance, and nitrogen balance.
• Intravenous administration of the amino acid mixture yielded comparable results to oral intake without apparent adverse effects.
• Cystine could replace methionine for short periods but led to tissue catabolism; its addition to a protein-free diet induced temporary plasma protein synthesis (cystine effect).
• Arginine was essential for plasma protein synthesis but not nitrogen balance in the short term.
• Omission of threonine or valine rapidly decreased plasma protein formation and nitrogen balance.
• Exclusion of histidine, arginine, and most lysine allowed nitrogen balance and weight maintenance for a week but significantly reduced plasma protein production.

Conclusions:

• A balanced mixture of essential crystalline amino acids is as effective as dietary protein for plasma protein synthesis and maintaining physiological homeostasis.
• Specific amino acids (threonine, valine, arginine, histidine, lysine) play critical roles in protein metabolism and are required for optimal plasma protein production.
• The crystalline amino acid mixture holds significant potential for transfusion and infusion therapies in conditions involving nitrogen deficiency, tissue injury, or accelerated nitrogen loss.