Ingested protein dose response of muscle and albumin protei - PowerPoint Presentation

Slide1

Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men

Presented by Leanne Gravette, Jeff

Gibberman

, Zoe Fisher-FalkSlide2

BackgroundAmerican

Journal of Clinical

Nutrition

Published

in

2009

.

Authors: Daniel R. Moore,

Meghann

J. Robinson, Jessica L. Fry, Jason

E.Tang

, Elisa I. Glover, Sarah B. Wilkinson, Todd Prior, Mark A.

Tarnopolsky,and

Stuart M. PhillipsSlide3

1st of it’s kind

1

st

study to measure a “

dose-response relation between ingested whole protein and muscle protein synthetic rates after resistance exercise”

(Moore, et al 161).

Past studies have proved a dose response at rest, but never after resistance exercise.Slide4

Background

There is a correlation between amino acid intake and enhanced anabolic effect of resistance exercise on muscle

.Slide5

Points of interest

H

ow do specific doses of whole protein intake affect

muscle protein synthesis

(MPS) and

albumin protein synthesis

(APS)?Does the dose intake enhance phosphorylation of the candidate signaling proteins?

Does albumin act as a protein storage system in times of excessive protein intake?How is this possible phenomenon tied in to increase in albumin synthesis?Slide6

The pathwaymTOR

Signaling Pathway

Pathway towards MPS

Contains regulatory proteins

Candidate signaling proteins

Changes in MPS may be regulated by these target proteins

“Stimulation of MPS in humans after feeding or resistance exercise is accompanied by enhanced

phosphorylation, and presumably activity, of the mTOR signaling pathway.”Slide7

All about albumin

Albumin unaffected by resistance exercise in young men.

Albumin synthesis stimulated by increased availability of amino acids.

Can dietary amino acids be incorporated into albumin protein in an effort to minimize their irreversible oxidation?

Feeding induced increase in albumin protein synthesis may serve as “storage’’ until amino acids are needed in periods of reduced supply.Slide8

Hypothesis

Mixed MPS will demonstrate a dose response to dietary protein after resistance exercise.

The maximal effective (maximally stimulated MPS) dose will be similar to what has previously been reported to be maximal at rest.

Plasma albumin protein synthesis will display a similar dose response to dietary protein as mixed muscle protein.

Above an ingested dose of protein that maximally stimulated muscle and albumin protein synthesis, amino acid oxidation will increase.Slide9

summary of other areas of interest

The response of MPS to both feeding and exercise is regulated by specific protein kinases in the

mTOR

signaling pathway. Is there increased phosphorylation in response to increased dietary protein?

I

s there a direct relationship between increased dietary protein intake and increased phosphorylation

?

Can excess dietary amino acid be stored by albumin protein after increased APS?Slide10

Test SubjectsSix healthy

,

active males

Age

: 20-24yrs

Weight

174-205lbs approxHeight: 5’7’’-6’3”At least 4 months

previous recreational weightlifting experience. Slide11

Methods

Subjects performed exercise, ingested variable quantities of whole protein and then were tested for increases in MPS, APS and oxidation.

In this experiment

Leucine

was used as a tracer. This means that a stable isotopic form of

leucine

( [1-13C] leucine), not usually found in the body was used to track what happened to the protein ingested post-exercise.Leucine chosen b/c it is a EAA and a BCAA, primarily metabolized in skeletal muscle. Slide12

Procedure

The subjects were tested

five

times

with at least

one week between each trial. The trial consisted of

intensive leg resistance exercises that were designed to max out their physical capabilities. After exercise a catheter was inserted in each arm, one was used for taking blood samples and the other was used to inject the

leucine

tracer into the blood stream.

This was

followed immediately by an

ingestion of an egg protein drink

. The protein content for each participant

varied

between

0, 5, 10, 20 and 40 grams

of dietary whole protein. Slide13

Procedure cont.

In order to determine the physiological response to the ingested protein they used various methods of

analyzing blood, breath, and muscle

samples

Blood samples were taken from the catheterized arm

Breath was collected to determine CO2 enrichment

Muscle biopsy was taken twice (ouch!) at 1 and 4 hours from exercise

They took a ton of measurement from all these samples using many different devices.Slide14

Measurement devices

Isotope ratio mass spectrometry

CO2 enrichment in breath sample

Standard radioimmunoassay kit

Plasma insulin concentration

Standard glucose peroxidase enzymatic kit

Blood glucose concentration

Standard spectrophometric kitPlasma urea concentrationGas chromatography-mass spectrometryPlasma enrichmentSlide15

More measurement devicesCation

exchange chromatography

Free amino acid purification

Combustion-isotope ratio mass spectrometry

Amino acid conversion

Bicinchoninic

acid protein

assayDetermines protein contest of homogenatesGC-combustion-isotope ratio mass spectrometry

Liberates bound amino acidsSlide16

Results

Direct

correlation of increased dietary protein and MPS and APS up until 20 grams of ingested egg protein

.

At 40

grams, no

change in MPS or APS, however there was greater measure of leucine

oxidation.demonstrates that albumin does not actually store excess dietary amino acids. No noticeable increase in

phosphorylation

of the protein

kinases

in the

mTOR

signaling pathway as a direct result of increased protein intake. Slide17

Albumin Protein SynthesisSlide18

Muscle Protein SynthesisSlide19
Slide20

LimitationsSmall

sample size

6

people to represent the

population

young and active men only. The study is nonspecific about the

level of fitness and capability of each individual. What is the change of maximal protein utilization in people of various size

(ex: Jeff vs. Leanne)Slide21

Future ResearchResearchers proposed the possibility that ingesting

20 grams of protein, the peak amount for MPS and APS stimulation, five to six times

daily would maximize utilization of ingested protein

.

With a stronger study in this area one could provide empirical evidence to convince people to eat an optimal amount of protein.Slide22

RelevanceDetrimental

effects of overconsumption of animal protein

.

Ex: Met from meat

Osteoporosis

Atherosclerosis

Excess dietary AA get oxidized and stored as fat.