EFFECTS OF INFUSED SODIUM-ACETATE, SODIUM LACTATE, AND SODIUM BETA-HYDROXYBUTYRATE ON ENERGY-EXPENDITURE AND SUBSTRATE OXIDATION RATES IN LEAN HUMANS

Infusion of sodium acetate in lean humans results in a decrease in res piratory exchange ratio. which may be advantageous in patients with re spiratory failure. However, this potential decrease in respiratory wor k was observed to be offset by significant thermogenesis. The metaboli c effects of sodium acetate, sodium lactate, and sodium beta-hydroxybu tyrate, infused at a rate of 20 mumol . kg-1 . min-1 for 3 h, was moni tored in six healthy human volunteers. Respiratory exchange ratio decr eased from 0.85 +/- 0.02 at baseline to 0.75 +/- 0.02, 0.75 +/- 0.02, and 0.80 +/- 0.02, after acetate, lactate, or beta-hydroxybutyrate, re spectively (P < 0.05 for each). Acetate produced a larger thermic effe ct (22.7% of energy infused) than did lactate (16.3%) or beta-hydroxyb utyrate (13.6%). Thus, sodium salts of organic acids may potentially d ecrease the respiratory requirements by decreasing the respiratory exc hange ratio. However, this effect is partially offset by the thermic e ffect of these substrates. The maximal doses and safety of these anion s during larger infusion periods remain to be determined.