Mikkelsen E, Andersson K E, Lederballe Pedersen O
Acta Pharmacol Toxicol (Copenh). 1979 Feb;44(2):110-9. doi: 10.1111/j.1600-0773.1979.tb02304.x.
Ring preparations of human mesenteric arteries and veins were contracted by noradrenaline (1.8 x 10(-5)M) or potassium (127mM). Isometric tension was recorded. In the arterial preparations, the maximum response to noradrenaline was 97 +/- 8% (mean +/- S.E.M.) of that to potassium. In the veins, the corresponding figure was 38 +/- 4%. The calcium antagonists verapamil (2.2 x 10(-7)-2.2 x 10(-5)M) and nifedipine (2.9 x 10(-8)-2.9 x 10(-6)M) relaxed both arteries and veins contracted by noradrenaline or potassium, and reduced the responses to these agents when added 15 min. before stimulation. The time course of relaxation of potassium contracted preparations, induced by verapamil and nifedipine, was more rapid and complete than that produced by a calcium-free, high potassium solution. In contrast to verapamil, nifedipine caused a more pronounced inhibition of the potassium than of the noradrenaline evoked contractions in both arteries and veins. After exposure to a calcium-free medium for 30 min., the arterial response to noradrenaline was significantly (P less than 0.05) greater than that to potassium. However, the reverse was found in the veins. In both types of vessel, verapamil (2.2 x 10(-6)M) and nifedipine (2.9--10(-7)M) were equi-effective in reducing the noradrenaline reactivity, not only between mesenteric arteries and veins, but also between, e.g. peripheral and mesenteric vessels. The calcium antagonists nifedipine and verapamil do not have an identical mode of action. However, both agents seem to inhibit influx of extracellular calcium, and might also have an inhibitory effect on the release of intracellular calcium.
人肠系膜动脉和静脉的环行标本可被去甲肾上腺素（1.8×10⁻⁵M）或钾离子（127mM）收缩。记录等长张力。在动脉标本中，对去甲肾上腺素的最大反应为对钾离子反应的97±8%（平均值±标准误）。在静脉中，相应的数值为38±4%。钙拮抗剂维拉帕米（2.2×10⁻⁷ - 2.2×10⁻⁵M）和硝苯地平（2.9×10⁻⁸ - 2.9×10⁻⁶M）可使被去甲肾上腺素或钾离子收缩的动脉和静脉舒张，并在刺激前15分钟加入时降低对这些药物的反应。维拉帕米和硝苯地平诱导的钾离子收缩标本的舒张时程比无钙高钾溶液产生的舒张时程更快且更完全。与维拉帕米相反，硝苯地平在动脉和静脉中对钾离子诱发的收缩的抑制作用比对去甲肾上腺素诱发的收缩更明显。在无钙培养基中暴露30分钟后，动脉对去甲肾上腺素的反应显著（P＜0.05）大于对钾离子的反应。然而，在静脉中情况相反。在两种类型的血管中，维拉帕米（2.2×10⁻⁶M）和硝苯地平（2.9×10⁻⁷M）在降低去甲肾上腺素反应性方面等效，不仅在肠系膜动脉和静脉之间，而且在例如外周血管和肠系膜血管之间也是如此。钙拮抗剂硝苯地平和维拉帕米的作用方式并不相同。然而，两种药物似乎都抑制细胞外钙的内流，并且可能对细胞内钙的释放也有抑制作用。
