Vol. 89, Issue 6, 2268-2275, December 2000
Pharmacological characterization of vasomotor activity of
human musculocutaneous perforator artery and vein
Jianrong
Zhang1,
Joan E.
Lipa1,2,
Claire E.
Black1,2,
Ning
Huang1,
Peter C.
Neligan1,2,
Francis T. K.
Ling1,
Ronald H.
Levine2,
John L.
Semple2, and
Cho Y.
Pang1,2,3
1 Research Institute, Hospital for Sick Children, and
Departments of 2 Surgery and 3 Physiology, University
of Toronto, Toronto, Ontario, Canada M5G 1X8
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 impression 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 differences in sensitivity to
vasoconstrictors and vasodilators between the human musculocutaneous perforator (MCP) artery and vein by measuring the isometric tension of
arterial and venous rings suspended in organ chambers. Vascular contraction 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 × 10
9 M) of
endothelin-1 (ET-1). We observed that the vasoconstrictor potency of
norepinephrine was significantly higher in the MCP vein than in the MCP
artery. The vasoconstrictor potency of ET-1 and the thromboxane
A2 mimetic U-46619 were similar in the MCP vein and artery,
but the maximal contraction induced by ET-1 and U-46619 was
significantly higher in the MCP vein than in the MCP artery. On the
other hand, the MCP vein was less sensitive than the MCP artery to the
relaxation effect of nitroglycerin, nifedipine, and lidocaine. These
differences between the human MCP artery and vein in response to
vasoactive agents lend support to the clinical impression in flap
surgery that veins appear to be more susceptible to vasospasm than
arteries and venous vasospasm seems to be more difficult to resolve
than arterial vasospasm in cutaneous and musculocutaneous flap surgery.
tissue transplant; free flap; microvascular surgery; vasospasm; ischemic necrosis
