Open AccessEffect of light‐load resistance exercise on postprandial amino acid transporter expression in elderly men
Author(s) -
Agergaard Jakob,
Bülow Jacob,
Jensen Jacob K.,
Reitelseder Søren,
Bornø Andreas,
Drummond Micah J.,
Schjerling Peter,
Holm Lars
Publication year - 2017
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13444
Subject(s) - postprandial , supine position , endocrinology , medicine , skeletal muscle , messenger rna , leg press , bolus (digestion) , placebo , western blot , protein expression , whey protein , chemistry , resistance training , biochemistry , pathology , gene , alternative medicine , insulin
An impaired amino acid sensing is associated with age‐related loss of skeletal muscle mass. We tested whether light‐load resistance exercise ( LL ‐ RE ) affects postprandial amino acid transporter ( AAT ) expression in aging skeletal muscle. Untrained, healthy men (age: +65 years) were subjected to 13 h of supine rest. After 2 1/2 h of rest, unilateral LL ‐ RE was conducted (leg extensions, 10 sets of 36 repetitions) at 16% 1 RM . Thereafter, the subjects were randomized into groups that orally ingested 40 g of whey protein either as hourly drinks (4 g per drink) ( PULSE , N = 10) or two boluses (28 g at 0 h and 12 g at 7 h) ( BOLUS , N = 10), or hourly isocaloric maltodextrin drinks (placebo, N = 10). Quadriceps muscle biopsies were taken at 0, 3, 7, and 10 h postexercise from both the resting and exercised leg, from which the membrane protein and mRNA expression of select AAT s were analyzed by Western Blot and RT ‐ PCR , respectively. LAT 1 and PAT 1 protein expression increased in response to LL ‐ RE in the PULSE group, and SNAT 2 and PAT 1 protein expression increased in the BOLUS group when plasma BCAA concentration was low. In all three groups, LL ‐ RE increased LAT 1 mRNA expression, whereas a time course decrease in SNAT 2 mRNA expression was observed. LL ‐ RE increased membrane‐associated AAT protein expression and mRNA expression. Altered AAT protein expression was only seen in groups that ingested whey protein, with the greatest effect observed after hourly feeding. This points toward an importance of AAT s in the anabolic response following LL ‐ RE and protein intake.