Early changes in ATP and cyclic AMP levels in experimental critical skin flaps

A cranially based pedicle skin flap, 2 cm wide and 7 cm long, was prepared in the midline of the rat dorsum. The contents of ATP and cyclic AMP were determined in the proximal, middle and distal parts of the flap. The basal level of ATP was 1.3 +/- 0.1 nmol/g dry weight. Following the operation the level of ATP fell rapidly. The fall was more marked in those parts of the flap that eventually do not survive. During the first 12 h the level of cyclic AMP fell at least as rapidly. However, thereafter the cyclic AMP level remained constant or even increased while the ATP showed a further decrease. It is suggested that the rapid fall in ATP may be used to assess the eventual survival of skin flap. The results are also compatible with the opinion that a period of metabolic stimulation in the skin flap starts 12--18 h after operation, i.e. at the time when the adrenergic nerves in the flap degenerate.