Citrulline does not enhance blood flow, microvascular circulation, or myofibrillar protein synthesis in elderly men at rest or following exercise

2014 ◽  
Vol 307 (1) ◽  
pp. E71-E83 ◽  
Author(s):  
Tyler A. Churchward-Venne ◽  
Lisa M. Cotie ◽  
Maureen J. MacDonald ◽  
Cameron J. Mitchell ◽  
Todd Prior ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Blood Flow ◽  
Protein Synthesis ◽  
Whey Protein ◽  
Myofibrillar Protein ◽  
Microvascular Perfusion ◽  
Anabolic Resistance ◽  
Nonessential Amino Acids ◽  
Myofibrillar Protein Synthesis

Aging is associated with anabolic resistance, a reduced sensitivity of myofibrillar protein synthesis (MPS) to postprandial hyperaminoacidemia, particularly with low protein doses. Impairments in postprandial skeletal muscle blood flow and/or microvascular perfusion with hyperaminoacidemia and hyperinsulinemia may contribute to anabolic resistance. We examined whether providing citrulline, a precursor for arginine and nitric oxide synthesis, would increase arterial blood flow, skeletal muscle microvascular perfusion, MPS, and signaling through mTORC1. Twenty-one elderly males (65–80 yr) completed acute unilateral resistance exercise prior to being assigned to ingest a high dose (45 g) of whey protein (WHEY) or a low dose (15 g) of whey protein with 10 g of citrulline (WHEY + CIT) or with 10 g of nonessential amino acids (WHEY + NEAA). A primed, continuous infusion of l-[ ring-13C6] phenylalanine with serial muscle biopsies was used to measure MPS and protein phosphorylation, whereas ultrasound was used to measure microvascular circulation under basal and postprandial conditions in both a rested (FED) and exercised (EX-FED) leg. Argininemia was greater in WHEY + CIT vs. WHEY and WHEY + NEAA from 30 to 300 min postexercise ( P < 0.001), but there were no treatment differences in blood flow or microvascular perfusion (all P > 0.05). Phosphorylation of p70S6K-Thr389was greater in WHEY vs. WHEY + NEAA ( P = 0.02). Postprandial MPS was greater in WHEY vs. WHEY + CIT and WHEY + NEAA under both FED (WHEY: ∼128%; WHEY + CIT: ∼56%; WHEY + NEAA: ∼38%) and EX-FED (WHEY: ∼251%; WHEY + CIT: ∼124%; WHEY + NEAA: ∼108%) conditions ( P = 0.003). Citrulline coingestion with a low quantity of protein was ineffective in augmenting the anabolic properties of protein compared with nonessential amino acids.

scholarly journals Leucine-enriched amino acids maintain peripheral mTOR-Rheb localization independent of myofibrillar protein synthesis and mTORC1 signaling postexercise

2020 ◽  
Vol 129 (1) ◽  
pp. 133-143 ◽  
Author(s):  
Sarkis J. Hannaian ◽  
Nathan Hodson ◽  
Sidney Abou Sawan ◽  
Michael Mazzulla ◽  
Hiroyuki Kato ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Interactions ◽  
Human Skeletal Muscle ◽  
Myofibrillar Protein ◽  
Protein Protein Interactions ◽  
Peripheral Location ◽  
Mtorc1 Signaling ◽  
Myofibrillar Protein Synthesis

This is the first study to investigate whether postexercise leucine-enriched amino acid (LEAA) ingestion elevates mTORC1 translocation and protein-protein interactions in human skeletal muscle. Here, we observed that although LEAA ingestion did not further elevate postexercise MyoPS or mTORC1 signaling compared with placebo, mTORC1 peripheral location and interaction with Rheb were maintained. This may serve to “prime” mTORC1 for subsequent anabolic stimuli.

scholarly journals Presleep dietary protein-derived amino acids are incorporated in myofibrillar protein during postexercise overnight recovery

2018 ◽  
Vol 314 (5) ◽  
pp. E457-E467 ◽  
Author(s):  
Jorn Trommelen ◽  
Imre W. K. Kouw ◽  
Andrew M. Holwerda ◽  
Tim Snijders ◽  
Shona L. Halson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Dietary Protein ◽  
Myofibrillar Protein ◽  
Whole Body ◽  
Body Protein ◽  
Protein Ingestion ◽  
Casein Protein ◽  
The Impact ◽  
Myofibrillar Protein Synthesis

The purpose of this study was to determine the impact of ingesting 30 g casein protein with and without 2 g free leucine before sleep on myofibrillar protein synthesis rates during postexercise overnight recovery. Thirty-six healthy young men performed a single bout of resistance-type exercise in the evening (1945) after a full day of dietary standardization. Thirty minutes before sleep (2330), subjects ingested 30 g intrinsically l-[1-13C]phenylalanine-labeled protein with (PRO+leu, n = 12) or without (PRO, n = 12) 2 g free leucine, or a noncaloric placebo (PLA, n = 12). Continuous intravenous l-[ ring-2H5]phenylalanine, l-[1-13C]leucine, and l-[ ring-2H2]tyrosine infusions were applied. Blood and muscle tissue samples were collected to assess whole body protein net balance, myofibrillar protein synthesis rates, and overnight incorporation of dietary protein-derived amino acids into myofibrillar protein. Protein ingestion before sleep improved overnight whole body protein net balance ( P < 0.001). Myofibrillar protein synthesis rates did not differ significantly between treatments as assessed by l-[ ring-2H5]phenylalanine (0.057 ± 0.002, 0.055 ± 0.002, and 0.055 ± 0.004%/h for PLA, PRO, and PRO+leu, respectively; means ± SE; P = 0.850) or l-[1-13C]leucine (0.080 ± 0.004, 0.073 ± 0.004, and 0.083 ± 0.006%/h, respectively; P = 0.328). Myofibrillar l-[1-13C]phenylalanine enrichments increased following protein ingestion but did not differ between the PRO and PRO+leu treatments. In conclusion, protein ingestion before sleep improves whole body protein net balance and provides amino acids that are incorporated into myofibrillar protein during sleep. However, the ingestion of 30 g casein protein with or without additional free leucine before sleep does not increase muscle protein synthesis rates during postexercise overnight recovery.

scholarly journals Improved recovery from skeletal muscle damage is largely unexplained by myofibrillar protein synthesis or inflammatory and regenerative gene expression pathways

2020 ◽  
Author(s):  
George Frederick Pavis ◽  
Tom SO Jameson ◽  
Marlou L. Dirks ◽  
Benjamin P. Lee ◽  
Doaa Reda Abdelrahman ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Damage ◽  
Muscle Function ◽  
Nutritional Intervention ◽  
Myofibrillar Protein ◽  
Skeletal Muscle Damage ◽  
Amino Acid Availability ◽  
Expression Pathways ◽  
Myofibrillar Protein Synthesis

The contribution of myofibrillar protein synthesis (MyoPS) to recovery from skeletal muscle damage in humans is unknown. Recreationally active males and females consumed a daily protein-polyphenol beverage targeted at increasing amino acid availability and reducing inflammation (PPB; n=9), both known to affect MyoPS, or an isocaloric placebo (PLA; n=9) during 168 h of recovery from 300 maximal unilateral eccentric contractions (EE). Muscle function was assessed daily. Muscle biopsies were collected 24, 27, 36, 72 and 168 h for MyoPS measurements using 2H2O and expression of 224 genes using RT-qPCR and pathway analysis. PPB improved recovery of muscle function, which was impaired for five days following EE in PLA (interaction; P<0.05). Acute postprandial MyoPS rates were unaffected by nutritional intervention (24-27 h). EE increased overnight (27-36 h) MyoPS versus control leg (PLA: 33±19%; PPB: 79±25%; leg P<0.01), and PPB tended to increase this further (interaction P=0.06). Daily MyoPS rates were greater with PPB between 72-168 h after EE, albeit after function had recovered. Inflammatory and regenerative signaling pathways were dramatically upregulated and clustered following EE but were unaffected by nutritional intervention. These results suggest that accelerated recovery from EE is not explained by elevated MyoPS or suppression of inflammation.

scholarly journals Blood Flow Restriction Combined With Low-load Resistance-type Exercise Increases Myofibrillar Protein Synthesis Rates

2018 ◽  
Vol 50 (5S) ◽  
pp. 645-646
Author(s):  
Jean Nyakayiru ◽  
Cas J. Fuchs ◽  
Joey S.J. Smeets ◽  
Annemie P. Gijsen ◽  
Joy P.B. Goessens ◽  
...  
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Load Resistance ◽  
Myofibrillar Protein ◽  
Blood Flow Restriction ◽  
Flow Restriction ◽  
Low Load ◽  
Myofibrillar Protein Synthesis

scholarly journals Blood Flow Restriction Only Increases Myofibrillar Protein Synthesis with Exercise

2019 ◽  
Vol 51 (6) ◽  
pp. 1137-1145 ◽  
Author(s):  
JEAN NYAKAYIRU ◽  
CAS J. FUCHS ◽  
JORN TROMMELEN ◽  
JOEY S. J. SMEETS ◽  
JOAN M. SENDEN ◽  
...  
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Myofibrillar Protein ◽  
Blood Flow Restriction ◽  
Flow Restriction ◽  
Myofibrillar Protein Synthesis

scholarly journals Whey Protein Supplementation Preserves Postprandial Myofibrillar Protein Synthesis during Short-Term Energy Restriction in Overweight and Obese Adults

2014 ◽  
Vol 145 (2) ◽  
pp. 246-252 ◽  
Author(s):  
Amy J Hector ◽  
George R Marcotte ◽  
Tyler A Churchward-Venne ◽  
Caoileann H Murphy ◽  
Leigh Breen ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Whey Protein ◽  
Myofibrillar Protein ◽  
Protein Supplementation ◽  
Energy Restriction ◽  
Short Term ◽  
Obese Adults ◽  
Term Energy ◽  
Myofibrillar Protein Synthesis

scholarly journals Skeletal muscle IL-15/IL-15Rα and myofibrillar protein synthesis after resistance exercise

2017 ◽  
Vol 28 (1) ◽  
pp. 116-125 ◽  
Author(s):  
A. Pérez-López ◽  
J. McKendry ◽  
M. Martin-Rincon ◽  
D. Morales-Alamo ◽  
B. Pérez-Köhler ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Exercise ◽  
Myofibrillar Protein ◽  
Myofibrillar Protein Synthesis

scholarly journals Greater stimulation of myofibrillar protein synthesis with ingestion of whey protein isolate v. micellar casein at rest and after resistance exercise in elderly men

2012 ◽  
Vol 108 (6) ◽  
pp. 958-962 ◽  
Author(s):  
Nicholas A. Burd ◽  
Yifan Yang ◽  
Daniel R. Moore ◽  
Jason E. Tang ◽  
Mark A. Tarnopolsky ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Whey Protein ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Myofibrillar Protein ◽  
Elderly Men ◽  
Healthy Elderly ◽  
Micellar Casein ◽  
Myofibrillar Protein Synthesis

We aimed to determine the effect of consuming pure isolated micellar casein or pure whey protein isolate on rates of myofibrillar protein synthesis (MPS) at rest and after resistance exercise in elderly men. Healthy elderly men (72 (sem 1) years; BMI 26·4 (sem 0·7) kg/m2) were divided into two groups (n 7 each) who received a primed, constant infusion of l-[ring-13C6]phenylalanine to measure MPS at rest and during 4 h of exercise recovery. Participants performed unilateral leg resistance exercise followed by the consumption of isonitrogenous quantities (20 g) of casein or whey. Blood essential amino acids and leucine concentration peaked 60 min post-drink and were greater in amplitude after whey protein ingestion (both, P < 0·05). MPS in the rested leg was 65 % higher (P = 0·002) after ingestion of whey (0·040 (sem 0·003) %/h) when compared with micellar casein (0·024 (sem 0·002) %/h). Similarly, resistance exercise-stimulated rates of MPS were greater (P < 0·001) after whey ingestion (0·059 (sem 0·005) %/h) v. micellar casein (0·035 (sem 0·002) %/h). We conclude that ingestion of isolated whey protein supports greater rates of MPS than micellar casein both at rest and after resistance exercise in healthy elderly men. This result is probably related to a greater hyperaminoacidaemia or leucinaemia with whey ingestion.

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