Change in plasma amino acid concentrations during breath-hold diving at high altitude

We studied the plasma concentration of various amino acids in 6 Italian sport divers in Italy and at approximately 4,500 m altitude in Peru; 6 Peruvian inhabitants were examined for comparison. We attempted to create a situation of pronounced hypoxia in muscles by breath-hold diving at altitude. The diving reflex diverts blood away from muscles while diving increases central oxygen tension and prevents loss of consciousness. Differences in certain amino acids, probably related to diet, were noted between Italy and Peru. Increases in concentration of plasma alanine and some branched-chain amino acids occurred after breath-hold diving. These changes were similar to those seen after prolonged hard exercise, even though physical work was low. Hypoxia in muscles, common during hard work and during breath-hold diving at altitude, might thus be the stimulus for amino acid release from working muscles.