Effect of adrenergic stimulation on cutaneous microcirculation immediately after surgical adventitiectomy in a rat skin flap model

Chronic sympathetic denervation leads to the development of supersentivity to adrenergic agents. Free flap surgery results in the disruption of the autonomic nerve fibers running along the anastomosed vessels. We therefore investigated the early effect of surgical sympathectomy on the reactivity of cutaneous microcirculation challenged to adrenergic agents. Two epigastric flaps were elevated and exposed in 15 rats. On the right flap (Side A), a circular adventitiectomy of the feeder vessels was realized to provide surgical sympathectomy. On the left flap (Side N), vessels were kept intact. The following drugs were then given intravenously successively: phenylephrine (10 and 15 mu g kg(-1)), norepinephrine (10 mu g kg(-1)), prazocin (1 mg kg(-1)) followed by norepinephrine (10 mu g kg(-1)). Cutaneous microcirculation was assessed using Laser-Doppler Flowmeters simultaneously on the two flaps after each drug administration. Mean arterial pressure was also measured. On side N, phenylephrine and norepinephrine resulted in a transient increase in cutaneous microcirculation followed by a more prolonged reduction. On side A, only the initial increase was observed, which was greater and longer as compared with side N, and paralleled the increase in mean arterial pressure. After prazocin pre-treatment, norepinephrine produced a transient increase in cutaneous microcirculation similar on both sides, and parallel to the changes in arterial pressure. No decrease in cutaneous microcirculation was observed. Immediately after surgical adventitiectomy, the vasoconstriction produced by a-adrenergic agents is prevented. No denervation-induced hypersentivity is observed. Surgical sympathectomy might protect cutaneous flaps from vasoconstriction induced by endogenous catecholamines release. (C) 2008 Wiley-Liss, Inc.