Aging and intraspecific interactions in acute hypoxic survival of specific pathogen free OF1 mice of both sexes.

In light-synchronized pathogen-free OF1 mice, and LD50 acute hypoxic challenge was performed during the light period in which respiratory and motor activities are minimal. In males and females acute hypoxic resistance decreases with age. Grouping by ten significantly decreases hypoxic survival in young, adult, and senescent males, and in young females. In young mice, hypoxic survival is significantly less in males than in females, whether or not they have interindividual contacts. This sex-related difference disappears with aging in separated individuals, but remains in 230- and 420-day-old mice when there are interindividual contacts.