Effects of exercise, vitamin E, and ozone on pulmonary function and lipid peroxidation.

Expired pentane, an index of lipid peroxidation, and pulmonary function were measured as a function of exercise for 1 h with and without exposure to 0.3 ppm ozone. In experiment 1, 10 subjects who exercised on a bicycle ergometer at 50% of maximal oxygen consumption while being exposed to 0.3 ppm ozone had increased lung residual volume and decreased vital capacity, maximal midexpiratory flow rate, and forced expiratory volume in 1 s. In experiment 2, breath collected into a spirometer filled with hydrocarbon-scrubbed air showed increased pentane from the stress of exercise but no effect of ozone. During rest and exercise in experiment 3, two of six subjects had higher pentane levels than the other subjects. Following daily supplementation with 1,200 IU dl-alpha-tocopherol for 2 wk, the mean production of pentane during rest and exercise was significantly lowered, and there was no difference in pentane production among the subjects. It was concluded that lipid peroxidation occurs during exercise and that it is attenuated by vitamin E.

Effect of vitamin E and ozone on pentane and ethane expired by rats.

Pentane and ethane, which arise during lipid peroxidation in vivo, were measured by gas chromatography in breath samples of rats fed for 8 weeks a vitamin E-deficient diet to which had been added 0, 11, or 40 IU vitamin E acetate per kg. Further lipid peroxidation was induced by exposure of individual rats to 1 ppm ozone for 60 min. Nonparametric statistical analysis of the data for pentane expired before exposure of rats to ozone gave alpha values (alpha = 2P) of 0.006 when the O vitamin E group was compared with either of the vitamin E-supplemented groups. For ethane, comparison of the O vitamin E group with the groups supplemented with 11 and 40 IU vitamin E/kg of diet were 0.0294 and 0.0080, respectively. Alpha values less than .05 were considered significant. After a 60-min exposure of rats to 1 ppm ozone, the paired t-test showed pentane to be significantly (P less than .005) increased in only the rats fed the vitamin E-deficient diet.

Hydrocarbon gases produced during in vitro peroxidation of polyunsaturated fatty acids and decomposition of preformed hydroperoxides.

Hydrocarbon gases have been used previously as an index of lipid peroxidation in vivo and in vitro. In vitro experiments are reported on the formation of hydrocarbon gases from peroxidizing omega-3 and omega-6 fatty acids. Hydrocarbon gases were not released during a 20-hr peroxidation phase but were released following the decomposition of hydroperoxides by addition of excess ascorbic acid. The major hydrocarbon gas products in iron, copper, or hematin catalyzed peroxidation systems were ethane or ethylene from linolenic acid, and pentane from linoleic acid and arachidonic acid. Calculations of the ratios of hydrocarbon gases formed were based on fatty acid decrease and/or change in diene conjugation and peroxide values. Depending on the fatty acid, catalyst, and calculation basis used, pentane formation was as high as 1.3 mol %, ethane 4.3 mol %, and ethylene 10.6 mol %.

Effect of dietary vitamin E on expiration of pentane and ethane by the rat.

An analytical method for the measurement of hydrocarbon gases in the breath of rats is described. The method was used to follow the expiration in rat breath of in vivo formed scission products of hydroperoxides. The major products are pentane from the linoleic acid family and ethane from the linolenic acid family. Rats were fed 0, 11 or 40 i.u. vitamin E acetate/kg diet for 7 wk starting at age 21 days. Data obtained by gas chromatographic analysis of breath samples were analyzed by the Mann-Whitney nonparametric U-test. This statistical analysis showed that pentane evolved by the group of rats not supplemented with vitamin E was significantly higher during the period 1-7 wk than that evolved by either of the two supplemented groups of rats. Ethane from the nonsupplemented group was significantly higher than that from the group supplemented with 40 i.u. vitamin E/kg of diet by 5 wk, and significantly high than both supplemented groups by 6 wk. By 7 wk, pentane production was tenfold greater in the non-supplemented group, and ethane was about twofold greater. There was no significant difference between the groups supplemented with 11 and 40 i.u. vitamin E/kg diet for either ethane or pentane. This new technique, which measures scission products from in vivo lipid peroxidation, promises to be useful for application to many experimental areas where lipid peroxidation is expected or known to occur.