Key result
Lidocaine exerts biphasic vascular effects with low-dose contraction and high-dose relaxation, unlike CGRP-mediated vasodilation alone.
Why the study?
Vasoconstriction during and after microsurgery may cause hypoperfusion and flap necrosis, necessitating investigation of vasodilators lidocaine and CGRP on human radial arteries.
What are the vascular effects of lidocaine and CGRP on isolated human radial arteries?
What are the vascular effects of lidocaine and CGRP on isolated human radial arteries?
Lidocaine exhibits contractile effects at low concentrations in human radial arteries, suggesting caution when used as a vasodilator in microsurgery, whereas CGRP provides consistent relaxation.
Answers are grounded in this paper and cite their sources.
These in vitro effects should not guide clinical dosing; hypothesis-generating for lidocaine and CGRP in microvascular research.
Vasoconstriction during and after microsurgery may cause hypoperfusion and result in flap necrosis. This study investigated the vascular effects of two known vasodilators: lidocaine and the naturally-occurring substance, calcitonin gene-related peptide (CGRP). Experiments were performed in vitro on 47 human radial arterial rings from 18 patients undergoing reconstruction after head and neck tumor surgery with free radial forearm flaps. Lidocaine produced a biphasic dose-response curve, with contraction at low concentrations (1.5 x 10(-5) to 1.5 x 10(-3) M) and relaxation at higher concentrations (4.5 x 10(-3) to 1.5 x 10(-2) M). It caused significantly stronger contractions in arteries with mechanically removed endothelium, compared with arteries with intact endothelium. Prolonged rebound contraction occurred when the lidocaine concentration was decreased. Lidocaine also potentiated noradrenaline-induced contraction. CGRP produced only dose-dependent relaxation of constricted radial arteries at low concentrations (3 x 10(-10) to 10(-7) M). The contractile effects of lidocaine should be considered when a vasodilative substance is required.
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Jernbeck et al. (1993) studied Patients undergoing reconstruction after head and neck tumor surgery (n=18). Lidocaine and Calcitonin Gene-Related Peptide (CGRP) was evaluated on Vascular effects (contraction and relaxation). Lidocaine produced a biphasic dose-response curve with contraction at low concentrations and relaxation at higher concentrations, whereas CGRP produced only dose-dependent relaxation.
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