Hypoxia and Anoxia Tolerance in Animals: Mechanisms and Biomedical Applications

Hypoxia

A condition where tissues are exposed to low O2, occurring when arterial O2 saturation (SPO2) falls below 90%.

Anoxia

A condition where the body receives no O2, sometimes referred to as 'extreme Hypoxia.'

Dyspnea

Shortness of breath.

Tachycardia

Fast heart rate.

Cyanosis

Blue/grayish skin.

Neurological impairment

A variety of issues resulting from prolonged exposure to low O2.

Ataxia

Inability to coordinate limbs.

Myoclonus

Muscle weakness, tremors, or jerky movements.

Naked Mole Rat (NMR)

Most hypoxia-tolerant mammal, capable of surviving in 0% O2 for 18 minutes.

Fructolysis

Mechanism where NMRs convert to Fructolysis to continue energy production when glycolysis fails.

Metabolic Rate Depression

Mechanism that conserves energy by reducing metabolic rates by up to 85%.

Behavioral and Thermal Regulation

Mechanism that maintains stable body temperature in various ways to promote homeostasis.

Painted Turtle

Most anoxia-tolerant tetrapod, can survive 0% O2 for over 4 months.

Brumation

A state of dormant hibernation where painted turtles stay buried in the mud.

Anaerobic Glycolysis

Primary energy pathway utilized in the absence of O2, executed by suppressing metabolism.

Metabolic Suppression

Mechanism that lowers ATP demand to match reduced ATP supply.

Bone Buffers

Mechanism where skeleton and shell act as an acid sink maintaining pH by neutralizing lactic acid.

Crucian Carps

Most anoxia-tolerant fish, can survive in 0% O2 for 4-6 months.

Maintained Cardiac Input

Mechanism that facilitates (near) normal cardiac output by maintaining and increasing cardiac input.

Ethanol Production and Secretion

Mechanism where carps convert lactate into excretable ethanol to avoid acidosis.

Increased GABA Levels

Mechanism that slows down energy usage and extensive apoptosis by inducing metabolic depression.