Sys S U, Boels P J, Brutsaert D L
Department of Physiology and Medicine, University of Antwerp, Belgium.
J Cardiovasc Pharmacol. 1987 Oct;10(4):445-9. doi: 10.1097/00005344-198710000-00010.
The question has been raised whether the in vivo positive inotropic effect of amrinone and milrinone is a primary effect or secondary to vasodilation. The effects of each drug on isolated trabeculae and resistance vessels obtained from the same dog hearts were determined separately. The positive inotropic and vasodilatory effects coincided over the same concentration range for amrinone. The active isometric force of trabeculae and resistance vessels was increased, and respectively decreased by 20% at comparable concentrations of amrinone--20% ED (effective dose) ranging between 9.5 and 18 microM. By contrast, the vasodilatory properties of milrinone (20% ED, 15-34 microM) appeared only at concentrations at which milrinone had already evoked a maximal positive inotropic response in trabecular muscle (20% ED, 0.36-0.38 microM). Based on the present experiments and their limitations, it would thus appear that, in the intact heart and at therapeutic doses, positive inotropic and vasodilatory effects may be equally present for amrinone, whereas, for milrinone, the positive inotropic effect would largely predominate the vasodilatory effect.
氨力农和米力农在体内的正性肌力作用是原发性作用还是血管舒张的继发作用，这一问题已被提出。分别测定了每种药物对从同一只犬心脏获取的离体小梁和阻力血管的作用。氨力农的正性肌力作用和血管舒张作用在相同浓度范围内一致。在氨力农浓度相当（有效剂量20%，即9.5至18微摩尔之间）时，小梁的主动等长力增加，阻力血管的主动等长力分别降低20%。相比之下，米力农（有效剂量20%，15至34微摩尔）的血管舒张特性仅在米力农已在小梁肌中引起最大正性肌力反应的浓度时才出现（有效剂量20%，0.36至0.38微摩尔）。基于目前的实验及其局限性，因此似乎在完整心脏和治疗剂量下，氨力农的正性肌力作用和血管舒张作用可能同样存在，而对于米力农，正性肌力作用在很大程度上占主导地位，超过血管舒张作用。
