Aminotriazole Effects on Lung and Heart H₂O₂ Detoxifying Enzymes and TBA‐RS at Two pO₂

Abstract

In order to clarify the physiological role in vivo of H2O2-detoxifying enzymes at low and high levels of O2 tension we studied catalase (CAT), glutathione peroxidases (GP), and in vivo peroxidation (TBA-RS) in the lung and heart of Rana perezi frogs chronically treated with hyperoxia, aminotriazole (AT) -a CAT inhibitor-, or both. Hyperoxia did not change CAT, GP or TBA-RS. Aminotriazole caused an almost complete depletion of CAT, a 30% decrease of GP and a 132% (lung) to 200% (heart) increase of TBA-RS. Changes similar to these were found in the group treated with AT in hyperoxia. No mortality or changes in total or organ weight occurred in the experimental groups. Main conclusions are: (1) The maximal hyperoxia tolerance showed by frogs among vertebrates does not need antioxidant enzyme induction from lung or heart and is probably related to the presence of high constitutive levels of GP in relation to metabolic rate. (2) Even in normoxia the tissues present significant amounts of H2O2, and CAT is needed to avoid oxidative damage. GP does not compensate its absence. The implications of these results in relation to oxygen toxicity in man is discussed.

Effect of aminotriazole on antioxidant defense system of tasar silkworm Antheraea mylitta

“…The findings of our investigation strongly corroborate the earlier reports of CAT inhibition by AMT in various animal models like fish and frog (Lopez-Torres et al 1990;Lushchak et al 2003;Bagnyukova et al 2005). In a recent study on cotton bollworm Helicoverpa armigera, Goud et al (2012) inhibited catalase by another catalase inhibitor, salicylic acid, and found that all eight isozymes observed in their study except cat1 (one of the isozymes of catalase)were inhibited by salicylic acid.…”

Physiological studies on the effect of copper nicotinate (Cu–N complex) on the fish, Clarias gariepinus, exposed to mercuric chloride

“…In addition, Lopes-Torres et al (1990) and Bagnyukova et al (2003) reported that catalase is the main H 2 O 2 -detoxyfying enzyme. The decreased CAT activity may be due to the flux of superoxide radicals, which have been shown to inhibit CAT activity (Stanic et al 2006).…”

Effects of prolonged exposure to low pH on enzymatic and non-enzymatic antioxidants in Japanese Medaka (Oryzias latipes)

“…The role of catalase in defense against peroxides is not fully understood. Some authors suggest that catalase is the main H 2 O 2 -detoxifying enzyme (Barja de Quiroga et al, 1988;López-Torres et al, 1990) and that it plays the major role in the decomposition of H 2 O 2 when its intracellular concentration is highly elevated (Hermes-Lima, 2005), while other studies found that GPx was more efficient at detoxifying H 2 O 2 (Remacle et al, 1992) and that low levels of H 2 O 2 are better controlled by GPx (Hermes-Lima, 2005). The catalase inhibition at pH 6.0 was probably compensated by the increase in both GPx activity and glutathione concentration.…”