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Protein ingestion impairs insulin‐stimulated net muscle carnitine uptake in healthy young men (LB812)
Author(s) -
Shan Chris,
Nixon Aline,
Greenhaff Paul,
Stephens Francis
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.lb812
Subject(s) - carnitine , ingestion , medicine , endocrinology , insulin , carbohydrate , chemistry
Carbohydrate ingestion promotes insulin‐mediated muscle carnitine accretion, but the effect of protein ingestion is unknown. Six healthy males (age 24 ± 5 yrs, BMI 23 ± 3 kg/m²) ingested 80g carbohydrate (CHO), 40g whey protein + 40g CHO (PRO), or flavoured water (CON) beverages (500 ml) 1 hr following ingestion of 3g L‐carnitine (0.1% ²H3‐L‐carnitine) on 3 randomised 3‐hr visits. The rate of disposal (Rd) and arterio‐venous (AV) forearm carnitine balance (determined from arterialised‐venous and venous plasma ²H3‐carnitine and carnitine concentrations), and brachial artery blood flow (BAF; Doppler ultrasound) were measured, together with serum insulin concentrations, at baseline and 20 min intervals for 3 hrs. Carnitine Rd at 100 min was 4.4 fold greater in CHO compared to CON (0.3 ± 0.1 vs 0.1 ± 0.1 µmol/min; P<0.05), which coincided with peak serum insulin concentration in CHO (64 ± 10 mU/L). However, despite similar insulin responses in CHO and PRO (3‐hr area under curve [AUC] was 4.6 ± 0.8 and 3.9 ± 0.7 U/L•min, respectively) compared to CON (0.4 ± 0.04 U/L•min; P<0.001) and increases in BAF (15 ± 3 and 12 ± 5%) above CON (P<0.05), net carnitine balance AUC increased in CHO (P<0.01), but not PRO, compared to CON (9.3 ± 4.0 and ‐3.9 ± 5.7 vs ‐1.2 ± 1.5 µmol•min, respectively) over the 2 hrs following beverage ingestion. Carbohydrate stimulates insulin mediated muscle carnitine balance, but protein may antagonise this process.