Effects of calcitonin gene-related peptide and lidocaine on mechanically-induced vasospasm in a rat island flap.

A neurovascular island flap based on the superficial epigastric vessels was raised in 59 rats. Blood flow in the flap was recorded continuously with a laser Doppler flowmeter. Complete vasospasm was induced mechanically in the artery by pinching it. Calcitonin gene-related peptide (10(-7) M), lidocaine 2 percent, lidocaine 20 percent, or sodium chloride 0.9 percent were applied topically to the vessels in order to relieve the vasospasm. In 18 arteries, spasm was induced a second time after the resolution of the first vasospasm. Calcitonin gene-related peptide significantly shortened the time to reach 50 percent of the original blood flow and increased the final blood-flow values 30 min after mechanically-induced vasospasm, in comparison with pre-spasm values, and significantly increased the number of flaps in which the blood-flow values were restored to pre-spasm levels. Lidocaine did not significantly change the time to reach 50 percent of the original blood-flow values and the number of flaps recovering to pre-spasm blood-flow levels, or the final levels after vasospasm, in comparison with saline. It was concluded that, in this model, calcitonin gene-related peptide, but not lidocaine, increased blood flow after mechanically-induced vasospasm.