Pharmacological characterization of vasomotor activity of human musculocutaneous perforator artery and vein

ical characterization of vasomotor activity of human muscu-locutaneous perforator artery and vein. J Appl Physiol 89: 2268–2275, 2000.—Vasospasm is one of the main causes of skin ischemic necrosis in cutaneous and musculocutaneous flap surgery, but the pathogenic mechanism is unclear. We planned to test the hypothesis derived from clinical impres-sion that veins are more susceptible to vasospasm than arteries in flap surgery and, once established, that venous vasospasm is difficult to resolve and more detrimental than arterial vasospasm. To this end, we investigated the differ-ences in sensitivity to vasoconstrictors and vasodilators be-tween the human musculocutaneous perforator (MCP) artery and vein by measuring the isometric tension of arterial and venous rings suspended in organ chambers. Vascular con-traction was expressed as a percentage of the tension induced by 50 mM KCl. Relaxation was expressed as a percentage of contraction induced by a submaximal concentration (3 3 1029 M) of endothelin-1 (ET-1). We observed that the vaso-constrictor potency of norepinephrine was significantly higher in the MCP vein than in the MCP artery. The vaso-constrictor potency of ET-1 and the thromboxane A2 mimetic U-46619 were similar in the MCP vein and artery, but th