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On the mechanism by which antiadrenergic drugs increase survival of critical skin flaps.

In order to asses the possibility that degeneration release of noradrenaline influences the survival of critical skin flaps, we studied the effect of various antiadrenergic drugs on skin-flap levels of noradrenaline, ATP, and cyclic AMP. Reserpine treatment depleted the skin flaps of noradrenaline and counteracted the fall in ATP and the cyclic AMP accumulation. Guanethidine had similar but less pronounced effects. Propranolol did not affect noradrenaline levels or depletion rate, but reduced the metabolic stimulation, as assessed by cyclic AMP levels in the flap. Phentolamine had no effect on basal noradrenaline levels, but tended to accelerate its disappearance and reduce lactate accumulation, a measure of hypoxia. All these drugs are known to increase skin-flap survival. It is suggested that they do so by, respectively, depleting the flap of its content of noradrenaline prior to operation or preventing the vasoconstriction and metabolic stimulation caused by released noradrenaline.