In vitro effects of aspirin on malondialdehyde formation and on activity of antioxidant and some metal-containing enzymes

Effects of Acetylsalicylic Acid Usage on Inflammatory and Oxidative Stress Markers in Hemodialysis Patients

The aims of this study were to determine the effects of acetylsalicylic acid (ASA) on inflammation and oxidative stress markers in hemodialysis (HD) patients and to examine the associations between these markers and the sociodemographic and clinical characteristics of participants. The study included 36 subjects who used 300 mg of ASA for 60 days. Inflammation and oxidative stress were assessed based on levels of biochemical markers. ASA usage promoted a decrease in high-sensitivity C-reactive protein (p = 0.01). The level of hydrogen peroxide increased after 30 days of use of ASA and subsequently decreased (p = 0.01). Reduced glutathione reduced at the end of the study (p < 0.01); the malondialdehyde level did not change and the levels of vitamins A and E were inverse to drug use (p = 0.01). ASA usage promoted reduced levels of inflammation, increased production of markers of oxidative stress, and reduced antioxidant defense.

Do zinc and selenium prevent the antioxidant, hepatic and renal system impairment caused by aspirin in rats?

Aspirin is widely used as an antiinflammatory drug especially in children with rheumatic fever arthritis. The diminishing effects of aspirin on antioxidant enzymes and hepato-renal systems at high doses are well-known. It is now evident that the damage at antioxidant system worsens the clinical picture of the disease and prolongs the treatment time. Thus, we investigated the effect of antioxidant enzyme cofactors-zinc and selenium-supplementation on superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) levels (erythrocyte and liver) and hepato-renal toxicity during aspirin treatment at therapeutic doses. The rats were divided into five groups. The first and second groups were given aspirin 75 mg/kg/day and aspirin plus selenium (Selenium 200, selenium 200 mg tablet as selenium yeast, GNC) and zinc (Zinc 100, zinc 100 mg tablet as zinc gluconate, GNC), respectively, the third and fourth take 50 mg/kg/day aspirin and aspirin plus selenium and zinc twice a day, respectively. The fifth group was control. The rats were treated with aspirin for 5 weeks as in the treatment of rheumatic fever arthritis in children. Erythrocyte SOD and MDA levels were preserved with supplementation, whereas there was no change for GSH-Px levels. Liver SOD, GSH-Px, and MDA levels were not changed. In zinc- and selenium-supplemented groups, the levels of serum alanine aminotransferase, uric acid, and direct bilirubin levels were found statistically decreased compared with nonsupplemented groups. There was no significant histopathologic change in specimens of hepatic and renal tissues. Trace element supplementation may prevent free radical damage and shorten treatment time in children using long-term aspirin treatment.

Aspirin impairs antioxidant system and causes peroxidation in human erythrocytes and guinea pig myocardial tissue

This study aims to investigate possible effects of aspirin treatment on cellular oxidant/antioxidant system. In the first part of the study, 15 guinea pigs were given aspirin at three different doses (2200, 440 and 10 mg/kg/day) for 30 days and five were fed on the same diet without aspirin. After a month, animals were killed and their hearts were removed for use in analyses. In the other part, after fasting blood samples were obtained from 11 volunteer subjects, they were given aspirin (approximately 10 mg/kg/day) for 30 days and second blood samples were obtained after 1 month. Five volunteer subjects also participated as placebo control. Oxidant/antioxidant parameters, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA), nonenzymatic superoxide scavenger activity (NSSA), susceptibility to oxidation (SO) and antioxidant potential (AOP) values, were assayed in the samples. Antioxidant system was found to be impaired in the heart tissue from guinea pigs and in the erythrocytes from volunteer subjects. AOP and NSSA values were lower and MDA higher after aspirin treatment in both heart tissues and erythrocytes. In guinea pig heart tissue, SO was lower, but GSH-Px and CAT were unchanged after aspirin treatment. In human erythrocytes, SO was unchanged, but GSH-Px and CAT activities were increased after aspirin treatment. Changes in guinea pig heart tissues from animals treated with higher aspirin doses were more drastic relative to those of human erythrocytes, but no meaningful differences were observed between analysis parameters of control and lower-dose (10 mg/kg/day) aspirin-treated animals. Our results suggest that high-dose aspirin exerts significant toxicity to guinea pig myocardium and normal dose aspirin may cause peroxidation in the human erythrocytes due to its oxidant potential. We suppose that antioxidant supplementation may be beneficial for the people using aspirin for longer periods in order to prevent peroxidation damages.

Determination of folate transport pathways in cultured rat proximal tubule cells

Deficiency of the vitamin folic acid has recently been linked with increased incidence of neural tube defects and of cardiovascular disease, through elevated plasma homocysteine levels. The kidney has an important role in conserving folate to counteract development of deficiency. Urinary folate excretion is regulated by the degree of reabsorption of folate by the proximal tubule cell. To evaluate an in vitro model for studies of the regulation of urinary folate excretion, the present studies examined the transport of 5-methyltetrahydrofolate (5-CH3-H4PteGlu), the primary form of folate in the glomerular filtrate, by normal rat proximal tubule (RPT) cells in confluent monolayer cultures. Specific binding of 5-CH3-H4PteGlu to the apical membrane was saturable (K(D) = 27 nM), but intracellular transport was not saturated up to 100 nM concentrations. 5-CH3-H4PteGlu transport was decreased 50% by concentrations of folic acid that completely blocked 5-CH3-H4PteGlu binding by the apical folate receptor. Probenecid (10 mM), an anion exchange (reduced folate carrier) inhibitor, reduced 5CH3-H4PteGlu transport by 50% without significantly affecting binding. Aspirin (3 mM) did not alter 5-CH3-H4PteGlu transport, but significantly enhanced the inhibition due to probenecid. Similarly, indomethacin (5 microM) potentiated the inhibition of 5-CH3-H4PteGlu transport by probenecid. These data suggest that RPT cells take up 5-CH3-H4PteGlu by both the folate receptor and the reduced folate carrier, implying a role for both pathways in regulating urinary folate excretion.

Aspirin protects low density lipoprotein from oxidative modification

OBJECTIVE

To examine the effects of aspirin on the potential for oxidative modification of low density lipoprotein (LDL).

DESIGN

Before and after trial.

SETTING

University department of medicine within a district general hospital campus.

PATIENTS

Ten healthy normolipidaemic volunteers drawn from laboratory and medical staff.

INTERVENTIONS

Aspirin (enteric coated) 300 mg daily for two weeks.

MAIN OUTCOME MEASURES

In vitro oxidation of LDL following ultraviolet C (UVC) irradiation with measurements made of malondialdehyde, conjugated dienes, and electrophoretic mobility.

RESULTS

There was a significant decrease in malondialdehyde production from LDL modified by aspirin in vivo following exposure to UVC irradiation for 90 minutes, culminating in a 30% decrease by 240 minutes (mean (SD) 64.2 (9.12) v 89.6 (11.6) nmol/mg LDL protein, P = 0.029). These observations were borne out using LDL modified by aspirin in vitro. The UVC induced increase in relative electrophoretic mobility of LDL was also significantly reduced following aspirin treatment (mean (SD) 2.17 (0.16) v 2.66 (0.24), P = 0.012).

CONCLUSIONS

Aspirin, both in vivo and in vitro, protects LDL against subsequent oxidative modification, providing an additional mechanism whereby aspirin may protect against atherosclerosis.