Effect of lidocaine on swine lingual and pulmonary arteries

Lidocaine has a biphasic action on smooth muscle of peripheral blood vessels, with vasoconstriction at low concentrations and vasodilation at higher concentrations. Many in vivo studies have demonstrated the effects of lidocaine on aortic or coronary arteries in several animals, but there are few reports about the effect on peripheral vessels. This study was designed to investigate the direct effects of lidocaine on peripheral vessels, namely swine lingual and pulmonary arterial rings.

Swine lingual artery and pulmonary artery segments, about 2-3 mm in diameter, were cut into 3-mm-long rings, and the lumen surface was gently rubbed to remove the endothelium. Isometric tension was measured using a displacement transducer and recorded. After a stable constriction was developed with 5 µM noradrenaline, 5 µM noradrenaline containing lidocaine (0.5, 1.0, 10, 20, 50 or 100 µg/ml) was perfused for 5 min, and then all drug perfusion was stopped. The strength of any isometric tension during an experiment was normalized to the strength of the isometric tension immediately before lidocaine perfusion, and expressed as a percentage.

Lidocaine elicited a concentration-dependent biphasic response of lingual and pulmonary arterial rings. The lidocaine concentration at 1 µg/ml caused mild contraction. Dilation occurred at 10 µg/ml and increased with increasing dose.

Lidocaine-induced vasoconstriction of swine lingual and pulmonary smooth muscle may occur at low concentration when lidocaine is infiltrated into the oral submucosa or administered intravenously for the treatment of ventricular arrhythmia.