Mitochondria in CR muscle support

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Mitochondria in CR muscle support

Hi All,

It seems from the below abstract that mitochondria are involved in muscle bulk

and

function that is dependent on adequate protein consumption and preserved with CR

in

the aged.

See the below abstract

Abstracts Presented at the 27th ESPEN Congress

Clin Nutr (2005) 24, 535–710, Abstract P092

A. Zangarelli, E. Chanseaume, B. Morio,

C. Brugere, L. Mosoni, P. Gachon, Y. Boirie,

S. Walrand

ENERGY RESTRICTION PRESERVES SKELETAL

MUSCLE MASS AND STRENGTH IN OLD RATS:

A MITOCHONDRIA-MEDIATED PROCESS?

Rationale: Changes in mitochondrial activity with

age may contribute to skeletal muscle mass and

function loss. Caloric restriction (CR) reverses some

age-related alterations in muscle mitochondrial

function but does not prevent the decline in ATP

production necessary to sustain muscle protein

synthesis rate (FSR) and contraction. We hypothe-sized

that improvement of mitochondrial activity

and FSR using a CR diet with usual protein intake

may enhance myofibrillar protein FSR and, conse-quently,

improve muscle mass and strength in old rats.

Methods: Wistar rats (16 month, n=30) were fed

either ad libitum (AL), 40% protein-energy re-stricted

(PER) or 40% energy restricted (ER) for 5

months. Muscle mass and strength were measured.

ATP production (luminometry), protein carbonyl

content (DNPH method) and FSR (using 13C-valine

as a tracer) were determined in tibialis anterior

muscle (TA) mitochondria. Myosin and actin FSR

were also investigated.

Results: ER diet improved mitochondrial ATP

production in TA (P<0.05 vs. AL). TA mitochondrial

FSR was also enhanced by ER diet (P<0.05 vs. PER

and AL) while PER decreased it (P<0.05 vs. AL).

Mitochondrial protein carbonyl content was de-creased

by food restriction (P<0.05 ER and PER vs.

AL). ER diet was able to maintain TA mass and to

improve myosin and actin FSR (P<0.05 vs. PER and

AL) and muscle strength (P<0.05 vs. AL).

Conclusions: Decreased oxidative damage to pro-teins

together with improvement of mitochondrial

function may explain the preservation of myofi-brillar

protein FSR and function with ER diet. In

conclusion, the synergistic effects of CR and

protein intake during aging may limit the progres-sion

of sarcopenia by optimizing the turnover rate

and the function of major proteins in muscle.

Al Pater, PhD; email: old542000@...

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