Re: Mitochondria in CR muscle support

August 9, 2005

There have been some recent posts suggesting that protein restriction

(sulfur-containing amino acids, in particular) may enhance longevity.

This study shows that protein restriction as contrasted with total

energy restriction [presumably of a balanced diet] is worse for

maintenance of muscle strength.

I hate it when studies of muscle development or maintenance do not

mention the amount of exercise that the exerimental animals were

subjected to. I am sure that it is a significant factor.

Tony

=========

--- In , Al Pater <old542000@y...>

wrote:

> 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@y...

>

> __________________________________________________

>

August 9, 2005