Enhanced anabolic response to milk protein sip feeding in elderly subjects with COPD is associated with a reduced splanchnic extraction of multiple amino acids.
OBJECTIVE
We previously observed in elderly subjects with Chronic Obstructive Pulmonary Disease (COPD) an enhanced anabolic response to milk protein sip feeding, associated with reduced splanchnic extraction (SPE) of phenylalanine. Milk proteins are known for their high Branched-chain Amino Acids (BCAA) content, but no information is present about splanchnic extraction and metabolism of the individual BCAA in COPD.


OBJECTIVE
To investigate whether BCAA metabolism and SPE of the individual BCAA are altered in COPD during milk protein sip feeding.


METHODS
In elderly subjects with COPD and in healthy age-matched elderly SPE, endogenous rate of appearance (Raendo) of the leucine (LEU), isoleucine (ILE) and valine (VAL) were measured before and during sip feeding of a Whey protein meal. To study the effect of aging, the healthy elderly were compared to a group of healthy young subjects. Stable isotopes of l-[(2)H(3)]-LEU, l-[1-(13)C]-ILE and l-[1-(13)C]-VAL were given on two separate test days orally or intravenously. Simultaneously, l-[ring-(2)H(5)]-phenylalanine (PHE) and l-[ring-(2)H(2)]-tyrosine (TYR) were given to determine the whole body protein breakdown (WbPB), synthesis (WbPS) and NetPS.


RESULTS
SPE of all BCAA, TYR, and PHE (p < 0.01) were lower in the COPD group, and the increase in netPS during feeding was higher in the COPD group (P < 0.01) due to higher values for PS (P < 0.001). Raendo of all BCAA, PHE and TYR were higher in the COPD than the healthy elderly group (P < 0.05) before and during feeding (P < 0.001). Sip feeding resulted in a reduction of Raendo of PHE, ILE and VAL (P < 0.05). Postabsorptive Raendo was not different for any of the measured amino acids between the healthy elderly and young group, while sip feeding resulted in a reduction of Raendo of PHE. Only SPE of TYR was higher in the elderly (P < 0.05) and the increase in netPS during sip feeding was independent of aging.


CONCLUSIONS
The enhanced anabolic response to milk protein sip feeding in normal-weight COPD patients is associated with a reduced splanchnic extraction of multiple amino acids including all branched-chain amino acids. Registration ClinicalTrials.gov = NCT01418469.
Center for Translational Research in Aging & Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, USA. mpkj.engelen@ctral.org
M P K J
MP
Engelen
C L N
CL
De Castro
E P A
EP
Rutten
E F M
EF
Wouters
A M W J
AM
Schols
N E P
NE
Deutz
D061605:Administration, Intravenous; D000284:Administration, Oral; D000368:Aged; D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage* / Q000097:blood; D001823:Body Composition; D001835:Body Weight; D006801:Humans; D007532:Isoleucine / Q000008:administration & dosage / Q000032:analysis; D007930:Leucine / Q000008:administration & dosage / Q000032:analysis; D008297:Male; D062407:Meals; D008875:Middle Aged; D008894:Milk Proteins / Q000008:administration & dosage* / Q000737:chemistry; D010649:Phenylalanine / Q000008:administration & dosage / Q000032:analysis; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000503:physiopathology*; D014443:Tyrosine / Q000008:administration & dosage / Q000032:analysis; D014633:Valine / Q000008:administration & dosage / Q000032:analysis; D000067816:Whey Proteins; D055815:Young Adult
D000597:Amino Acids, Branched-Chain; D008894:Milk Proteins; D000067816:Whey Proteins; D007532:Isoleucine; D014443:Tyrosine; D010649:Phenylalanine; D007930:Leucine; D014633:Valine