Branched-chain amino acids and arginine supplementation attenuates skeletal muscle proteolysis induced by moderate exercise in young individuals.

This study aimed at evaluating the effect of a single oral intake of branched-chain amino acids (BCAA) with Arg on skeletal muscle protein metabolism during moderate exercise in young individuals. Eight healthy volunteers (4 males and 4 females, means +/- SEM, 26 +/- 1 yrs, 177.8 +/- 3.7 cm, 72.6 +/- 3.9 kg) were studied in a randomized double-blind placebo-controlled cross-over trial. The subjects performed 3 bouts of 20-min cycling exercise (5-min break between each bout) at 126 +/- 13 W corresponding to 50 % of the maximal work intensity. A single oral supplement of either a BCAA drink containing 2 g of BCAA and 0.5 g of Arg or an isocaloric placebo drink was given at 10 min of the 1st exercise bout. Both arterial and venous blood samples were simultaneously taken from the radial artery and the femoral vein, respectively. Blood flow in the femoral artery was determined using the ultrasound Doppler technique. The blood sampling and blood flow measurements were performed at rest, every 10 min during each exercise bout. Net balance of BCAA and Phe across the leg muscles were measured by the arteriovenous difference method. The BCAA ingestion resulted in increases in both the plasma BCAA concentration and BCAA uptake into the working leg. The Phe release from the leg during exercise significantly increased as compared to the basal level in the placebo trial (0.97 +/- 0.28 vs. 0.23 +/- 0.22 micromol/min, p < 0.05). In the BCAA trial, the cumulative Phe release from the leg during the 3rd exercise bout was significantly lower than that in the placebo trial (5.0 +/- 7.4 vs. 35.9 +/- 13.2 micromol/25 min, p < 0.05). These results suggest that endurance exercise at moderate intensity enhances proteolysis in working muscles, and a single oral intake of 2 g of BCAA with Arg at onset of exercise effectively suppresses exercise-induced skeletal muscle proteolysis.

Infusion of vecuronium assessed by tactile evaluation of evoked thumb twitch.

In 15 patients (ASA I-II) undergoing intraabdominal gynaecological surgery, muscle paralysis for tracheal intubation and surgery was achieved by a combined bolus and demand infusion of vecuronium. The initial loading dose of 67 micrograms kg-1 and the rate of subsequent infusion were determined by evaluation of the tactile twitch response to train-of-four (TOF) stimulation of the ulnar nerve while the neuromuscular blockade obtained was recorded blindly for control on the contralateral arm. A maintenance dose of 4.9 mg h-1 (2.0-7.6 mg h-1) produced a smooth course of blockade with minimum and maximum values of twitch height during infusion of 2% and 12%, respectively. A period of 15.9 min elapsed from the end of infusion to a TOF-ratio of 0.7, when neostigmine 2.5 mg was administered at the point of two palpable twitches to TOF-stimulation. Simple tactile evaluation of peripheral nerve stimulation is sufficient to determine the infusion rate of vecuronium required to produce stable and appropriate neuromuscular blockade during intra-abdominal surgery.