Szocik J F, Gardner C A, Webb R C
Department of Anesthesiology, University of Michigan Medical School, Ann Arbor.
Anesthesiology. 1993 May;78(5):911-7. doi: 10.1097/00000542-199305000-00016.
Various local anesthetic agents have been shown to cause relaxation of isolated vascular segments contracted by catecholamines and other constrictor drugs. This report describes the actions of the amide-linked local anesthetic, bupivacaine, on adrenergic responsiveness of isolated arterial smooth muscle, and compares bupivacaine effects with those of lidocaine.
Helical strips of rat tail artery mounted in a muscle bath for measurement of isometric force generation were contracted in response to adrenergic nerve stimulation, increased potassium concentration, tyramine, or exogenous norepinephrine.
Treatment with bupivacaine or lidocaine caused depression of contraction to all four stimuli. Contraction to adrenergic nerve stimulation was more sensitive to the inhibitory effects of local anesthetics than was contraction to elevated potassium, tyramine, or exogenous norepinephrine. Furthermore, bupivacaine was more effective in reducing contraction to adrenergic nerve stimulation than was lidocaine (EC50: bupivacaine = 4 x 10(-6) M; lidocaine = 61 x 10(-6) M). In arteries incubated in solutions containing [3H]-norepinephrine and mounted for superfusion and isometric force recording, both bupivacaine and lidocaine (10(-5) M) depressed the contractions and diminished the release of radioactivity evoked by nerve stimulation. At the concentration tested, bupivacaine was more effective than lidocaine in reducing both contraction and the efflux of radioactivity as indicated by the magnitude of depression compared with control activities.
These findings suggest that lidocaine and bupivacaine depress adrenergic neurotransmission and inhibit smooth muscle contraction. Bupivacaine is a more potent inhibitor of adrenergic neurotransmission in the blood vessel wall than is lidocaine.
各种局部麻醉药已被证明可使由儿茶酚胺和其他缩血管药物引起收缩的离体血管段舒张。本报告描述了酰胺类局部麻醉药布比卡因对离体动脉平滑肌肾上腺素能反应性的作用，并将布比卡因的作用与利多卡因进行比较。
将大鼠尾动脉螺旋条安装在肌肉浴中以测量等长力产生，使其对肾上腺素能神经刺激、钾浓度升高、酪胺或外源性去甲肾上腺素产生收缩反应。
布比卡因或利多卡因处理导致对所有四种刺激的收缩反应受到抑制。与对钾浓度升高、酪胺或外源性去甲肾上腺素的收缩反应相比，对肾上腺素能神经刺激的收缩反应对局部麻醉药的抑制作用更敏感。此外，布比卡因在降低对肾上腺素能神经刺激的收缩反应方面比利多卡因更有效（半数有效浓度：布比卡因 = 4×10⁻⁶ M；利多卡因 = 61×10⁻⁶ M）。在含有[³H] - 去甲肾上腺素的溶液中孵育并安装用于灌注和等长力记录的动脉中，布比卡因和利多卡因（10⁻⁵ M）均抑制收缩并减少神经刺激引起的放射性物质释放。在所测试的浓度下，与对照活性相比，布比卡因在降低收缩和放射性物质流出方面比利多卡因更有效，这由抑制程度表明。
这些发现表明利多卡因和布比卡因抑制肾上腺素能神经传递并抑制平滑肌收缩。在血管壁中，布比卡因是比利多卡因更有效的肾上腺素能神经传递抑制剂。
