Relationship between plasma somatomedin activity and levels of cortisol and free fatty acids following stress in pigs.

Somatomedin activity, cortisol and free fatty acids have been measured in the plasma of eight Pietrain pigs at various times after stress. Somatomedin activity decreased immediately, reached a minimum after 15 min and remained low throughout a 3.5 h period Cortisol levels rose to a peak after 15 min and regained normal levels after 60 min. Free fatty acid levels increased to a peak level about 3 h after stress. The possibility of inhibitors of the bioassay for somatomedin activity influencing the results are discussed.