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L/2/11

MARZENA STANISZEWSKA

THE EFFECT OF HYPERBARIC AIR EXPOSURE ON CONCENTRATIONS
OF MALONDIALDEHYDE AND SOME PARAMETERS OF THE ANTIOXIDANT
SYSTEM IN RAT BLOOD

Summary
Hyperbaric air exposure (ExH) produces potentially harmful effects in organisms due to increased oxygen pressure and creates the risk of gas emboli during decompression. The effect of hyperbaric air exposure on free radical generation can be studied by varying the dynamics of tissue desaturation and total time of exposure to hyperbaric oxygen. The aim of the present study in rats was to (1) assess the effect of hyperbaric air exposures with accelerated decompression on free radical generation by measuring serum concentrations of malondialdehyde produced during β-elimination of polyunsaturated fatty and by determining the serum antioxidant status; and (2) examine the effect of hyperbaric air exposures on activities of the main antioxidant enzymes. The study was performed in 50 male Wistar rats dividet into one control (n = 10) and two study groups (II and III, n = 20 each). The study groups were divided into two equal subgroups (IIa, IIb, IIIa, IIIb) and exposed to hyperbaric air under maximal pressure of 6 ata, with a single session in group II and three session 60 minutes apart in group III. Subgroups IIa and IIIa underwent stepwise decompression during 101 minutes, while subgroups IIb and IIIb during 67 minutes. Serum concentrations of malondialdehyde (MDA), total antioxidant serum status (TAS), activities of antioxidant enzymes in serum (glutathione peroxidase (GPx)) and in erythrocytes (superoxide dismutase (SOD) and catalase (CAT)) were measured 30 min. from decompression. Mean MDA concentration in the control group was 0.691 ± 0.154 nmol/L. MDA concentrations in the study groups were higher by 22.2% in subgroup IIa (p < 0.001), 8.8% in IIb (n.s.), 44.5% in IIIa (p < 0.0005), and 14.7% in IIIb (n.s.). Concentrations of MDA in subgroups that underwent decompression for 101 minutes (IIa and IIIa) were higher than in subgroups that underwent decompression for 67 minutes (IIb and IIIb). Mean serum TAS values in the control group was 0.580 ± 0.077 nmol/L. TAS values in the study animals were as follows: subgroup lla - 94% of control value (n.s.), IIb – 104% (n.s.), IIIa – 85% (p < 0.05), and IIIb – 76% (p < 0.0005). Mean serum TAS were lower in subgroups IIIa and IIIb than in subgroups IIa and IIb (n.s., p < 0.0001, respectively). Activities of serum antioxidant enzymes were not altered after hyperbaric air exposure. Conclusions: 1. Hyperbaric air exposure of 6 ata with decompression that did not offer safe tissue desaturation enhanced lipid peroxidation and increased serum levels of malondialdehyde in rats. Concentration changes were related to the decompression regimen. 2. Three consecutive hyperbaric air exposures with 60-minute intervals and accelerated decompression produced deterioration in the antioxidant status of serum. 3. Hyperbaric air exposure with accelerated decompression did not affect activities of the main serum antioxidant enzymes, namely superoxide dismutase, glutathione peroxidase, and catalase.

K e y w o r d s : hyperbarism – rats – free radicals – malondialdehyde – total antioxidant status – antioxidant enzymes. 

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