Oxygen Toxicity / Free Radical

last updated: January 19, 2017

Orlando Debesa

Give me your tired, your poor,

your huddled masses yearning to breathe free,

The wretched refuse of your seeming shore.

Send these, the homeless, temptest-toss, to me.

--Emma Lazarus

Oxygen is Good

Essential for aerobic respiration

Generation of usable energy from food

Metabolism of endogenous intermediates

  • steroid hormones

  • prostaglandins

Endoplasmic Reticulum (ER)

  • most oxidized organelle in the cell

  • the formation of disulfide bonds for protein folding is guided by the oxidizing nature of the ER

Immune defense functions/cell killing / Inflammation

  • thru the formation of HOCl- by the phagocytes

  • NADPH oxidase generates superoxide

Generation of NO*

Metabolism of drugs/xenobiotics

Oxygen is bad

Hydroxyl ion (OH-)

  • DNA/protein damage

  • lipid peroxidation

H2O2

  • glutathione / catalase

Antioxidants

  • glutathione

... but I would more especially commend the clinician who, in acute diseases, by which the bulk of mankind are cutoff, conducts the treatment better than others.
 
Hippocrates, 400 BC