纳洛酮对犬内脏动脉平滑肌的作用。
The effects of naloxone on canine splanchnic arterial smooth muscle.
作者信息
Sasaki T, Kassell N F, Turner D M, Torner J C, Coester H C
出版信息
Proc Soc Exp Biol Med. 1984 Dec;177(3):422-7. doi: 10.3181/00379727-177-41967.
The pharmacological properties of naloxone on vascular smooth muscle in vitro were examined using canine mesenteric arterial segments. Naloxone exerted two different effects on the artery: (A) naloxone at a high concentration (3 X 10(-4) M) produced a nonspecific vasodilation; and (B) naloxone at lower concentrations (3 X 10(-7), 3 X 10(-6), and 3 X 10(-5) M) augmented the vasoconstrictor effects of epinephrine and norepinephrine without altering KCl- or serotonin-induced constriction. Naloxone's augmenting effect on epinephrine-induced constriction was dose dependent. Even when the arterial strips were incubated in low calcium (0.8 mM) or calcium free Kreb's solution, naloxone (3 X 10(-5) M) still augmented epinephrine-induced constriction. With respect to naloxone's effect on another alpha-adrenoreceptor agonist, naloxone (3 X 10(-5) M) failed to alter phenylephrine-induced constriction. Naloxone's augmenting effect on norepinephrine-induced constriction was abolished when the specimens were incubated with 10(-5) M normetanephrine, while naloxone (3 X 10(-5) M) still augmented the constriction even when the specimens were incubated with 10(-5) M cocaine. These results suggest that naloxone at lower concentrations may augment the constrictor responses to catecholamines, at least in part, by inhibiting the extraneuronal uptake of those catecholamines.
使用犬肠系膜动脉段研究了纳洛酮在体外对血管平滑肌的药理特性。纳洛酮对动脉产生两种不同的作用：(A)高浓度（3×10⁻⁴ M）的纳洛酮产生非特异性血管舒张；(B)较低浓度（3×10⁻⁷、3×10⁻⁶和3×10⁻⁵ M）的纳洛酮增强肾上腺素和去甲肾上腺素的血管收缩作用，而不改变氯化钾或血清素诱导的收缩。纳洛酮对肾上腺素诱导的收缩的增强作用呈剂量依赖性。即使将动脉条在低钙（0.8 mM）或无钙的克雷布斯溶液中孵育，纳洛酮（3×10⁻⁵ M）仍能增强肾上腺素诱导的收缩。关于纳洛酮对另一种α-肾上腺素能受体激动剂的作用，纳洛酮（3×10⁻⁵ M）未能改变去氧肾上腺素诱导的收缩。当标本与10⁻⁵ M去甲变肾上腺素孵育时，纳洛酮对去甲肾上腺素诱导的收缩的增强作用被消除，而即使标本与10⁻⁵ M可卡因孵育，纳洛酮（3×10⁻⁵ M）仍能增强收缩。这些结果表明，较低浓度的纳洛酮可能至少部分地通过抑制这些儿茶酚胺的非神经元摄取来增强对儿茶酚胺的收缩反应。
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