Post-meal responses of elongation factor 2 (eEF2) and adenosine monophosphate-activated protein kinase (AMPK) to leucine and carbohydrate supplements for regulating protein synthesis duration and energy homeostasis in rat skeletal muscle.

Previous research demonstrates that the anabolic response of muscle protein synthesis (MPS) to a meal is regulated at the level of translation initiation with signals derived from leucine (Leu) and insulin to activate mTORC1 signaling. Recent evidence suggests that the duration of the meal response is limited by energy status of the cell and inhibition of translation elongation factor 2 (eEF2). This study evaluates the potential to extend the anabolic meal response with post-meal supplements of Leu or carbohydrates.

Leucine content of dietary proteins is a determinant of postprandial skeletal muscle protein synthesis in adult rats.

Background: Leucine (Leu) regulates muscle protein synthesis (MPS) producing dose-dependent plasma Leu and MPS responses from free amino acid solutions. This study examined the role of Leu content from dietary proteins in regulation of MPS after complete meals.

Methods: Experiment 1 examined 4 protein sources (wheat, soy, egg, and whey) with different Leu concentrations (6.

Leucine or carbohydrate supplementation reduces AMPK and eEF2 phosphorylation and extends postprandial muscle protein synthesis in rats.

Muscle protein synthesis (MPS) increases after consumption of a protein-containing meal but returns to baseline values within 3 h despite continued elevations of plasma amino acids and mammalian target of rapamycin (mTORC1) signaling. This study evaluated the potential for supplemental leucine (Leu), carbohydrates (CHO), or both to prolong elevated MPS after a meal. Male Sprague-Dawley rats (∼270 g) trained to consume three meals daily were food deprived for 12 h, and then blood and gastrocnemius muscle were collected 0, 90, or 180 min after a standard 4-g test meal (20% whey protein).

Phenylbutyrate improves nitrogen disposal via an alternative pathway without eliciting an increase in protein breakdown and catabolism in control and ornithine transcarbamylase-deficient patients.

Background: Phenylbutyrate is a drug used in patients with urea cycle disorder to elicit alternative pathways for nitrogen disposal. However, phenylbutyrate administration decreases plasma branched-chain amino acid (BCAA) concentrations, and previous research suggests that phenylbutyrate administration may increase leucine oxidation, which would indicate increased protein degradation and net protein loss.

Objective: We investigated the effects of phenylbutyrate administration on whole-body protein metabolism, glutamine, leucine, and urea kinetics in healthy and ornithine transcarbamylase-deficient (OTCD) subjects and the possible benefits of BCAA supplementation during phenylbutyrate therapy.

Effect of parvoviral enteritis on plasma citrulline concentration in dogs.

Background: Plasma citrulline concentration is a reliable marker of global enterocyte mass in humans and is markedly decreased in diffuse small intestinal diseases. However, the relationship between acute intestinal damage and plasma citrulline concentration in dogs has never been documented.

Hypothesis: That dogs with parvoviral enteritis have a lower plasma citrulline concentration than healthy dogs and that plasma citrulline concentration is a predictor of death in puppies with parvoviral enteritis.