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Hypoxemic and ischemic tolerance in emperor penguins.
T Zenteno-Savin1, J St Leger, P J Ponganis
1CIBNOR-Planeacion Ambiental y Conservacion, Mar Bermejo 195, Playa Palo Santa Rita, La Paz, Baja California Sur, C.P. 23000, Mexico.
Comparative Biochemistry and Physiology. Toxicology & Pharmacology : CBP
|February 23, 2010
Summary
Emperor penguins exhibit elevated antioxidant enzyme activity, including catalase (CAT) and glutathione-S-transferase (GST), to prevent tissue damage from diving-induced hypoxemia and ischemia. These enzymes help mitigate reactive oxygen species (ROS) and re-perfusion injury.
Area of Science:
- Physiology
- Marine Biology
- Biochemistry
Background:
- Emperor penguins experience tissue hypoxia and ischemia during deep dives.
- This can lead to re-perfusion injury and damage from reactive oxygen species (ROS).
Purpose of the Study:
- To investigate the antioxidant defense mechanisms in emperor penguins.
- To compare their capacity to prevent re-perfusion injury and ROS damage with other bird species.
Main Methods:
- Assessed superoxide radical production and lipid peroxidation (TBARS) in muscle and liver biopsies.
- Measured antioxidant enzyme activities (CAT, GST, GPX) in emperor penguins, chickens, and other marine birds.
Main Results:
- Emperor penguins showed significantly elevated CAT and GST activity in muscle compared to all other species.
- Liver samples revealed elevated CAT activity and 2-3 times higher GST and GPX activity than other species.
- Superoxide production and TBARS levels were comparable across species.
Conclusions:
- Emperor penguins possess enhanced antioxidant enzyme systems, particularly CAT, GST, and GPX.
- These enzymes are crucial for scavenging ROS and preventing re-perfusion injury in diving birds.
- The potential for ROS formation is not reduced, but scavenging capacity is increased.
