EFFECT OF SIMPLE CARBOHYDRATES, CASEIN HYDROLYSATE, AND A LIPID TEST MEAL ON ETHANE EXHALATION RATE

Effect of simple carbohydrates, casein hydrolysate and a lipid test meal on ethane exhalation rate. J. Appl. Physiol. 76(3): 1119-1122, 1994. - To determine the potential differences in the effect of various nutrients on lipid peroxidation, the ethane exhalation (EE) rate, an index of lipid peroxidation, was measured in rats at 4 (young), 18 (intermediate age), and 24 (aged) mo of age at fasting conditions and after acute ingestion of various test meals. The EE rate (means +/- SD) after a 15-h fast was significantly reduced in 24-mo-old rats (2.45 +/- 0.44 pmol.min-1.100 g body wt(-1)) and 18-mo-old rats (3.51 +/- 0.55 pmol.min(-1) 100 g body wt(-1)) compared with 4-mo-old rats (4.44 +/- 0.66 pmol.min(-1) 100 g body wt(-1); P < 0.01). The EE rate significantly increased in 4-mo-old rats after ingestion of 50% (wt/vol) dextrose (8.59 +/- 2.9 pmol.min(-1).100 g body wt(-1)), 50% casein hydrolysate (6.77 +/- 1.23 pmol.min(-1).100 g body wt(-1)), and 20% neutral lipid emulsion (7.33 +/- 1.96 pmol.min(-1).100 g body wt(-1); P < 0.01). The response of aged rats to these nutrients compared with young rats was reduced by similar to 50%. A 25% dextrose solution or a 50% solution of sucrose, fructose, maltose, or galactose did not significantly alter EE rate. It is concluded that various macronutrients have a diverse potential of inducing lipid peroxidation. The responsiveness of aged rats to meal-induced enhancement of EE and presumably lipid peroxidation is significantly reduced.