Effect of carbon monoxide exposure on heart cytochrome c oxidase activity of rats.

The activity of cytochrome c oxidase in heart muscle of rats was within the control range 1 and 24 h after commencement of CO exposure (56% COHb) and was significantly decreased 3 h thereafter. A decrease of the enzyme activity was also detectable 3 h following repeated CO exposure demonstrating that cytochrome c oxidase does not seem to play a role in the adaptive response of organism to chronic CO exposure.