Vigholt Sørensen E, Nielsen-Kudsk F
Eur J Pharmacol. 1986 Jun 24;125(3):363-71. doi: 10.1016/0014-2999(86)90792-2.
The myocardial effects of g-strophanthin and the partial beta 1-adrenoceptor agonist xamoterol were compared to the effects of isoprenaline in the isolated spontaneously beating rabbit heart. Xamoterol and g-strophanthin both produced a distinct maximum increase in contractility as shown by the increase in isotonic contraction rate from 100 to 142% (pD2 7.51) and 151% (pD2 6.54), respectively, which was however less pronounced than the increase to 200% (pD2 7.81) caused by isoprenaline. The maximum chronotropic effect of xamoterol was moderate with a frequency increase from 100 to 128% (pD2 7.40) as was the increase in oxygen consumption to 130% (pD2 7.16), and no arrhythmias were seen. The positive inotropic range of g-strophanthin was very narrow (about 60-600 nM) and cardiac toxicity just overlapped and rapidly increased over this range. Xamoterol at a fixed concentration of 28 nM caused a rightwards shift of the isoprenaline concentration-response curves demonstrating the competitive beta 1-adrenoceptor blocking effect of the drug. G-strophanthin at a concentration of 268 nM acted additively with xamoterol with regard to maximum contractility and without causing any further increase in myocardial oxygen consumption except at the highest concentrations but there was a slightly increased nodal rhythm at xamoterol concentrations higher than about 20 nM.
在离体自发搏动的兔心脏中，比较了毒毛花苷G和部分β1肾上腺素能受体激动剂扎莫特罗对心肌的作用与异丙肾上腺素的作用。扎莫特罗和毒毛花苷G均使收缩性显著最大程度增加，等张收缩率分别从100%增加至142%（pD2 7.51）和151%（pD2 6.54），然而这一增加不如异丙肾上腺素引起的增加明显，后者增加至200%（pD2 7.81）。扎莫特罗的最大变时性效应适中，频率增加从100%至128%（pD2 7.40），耗氧量增加至130%（pD2 7.16），且未见心律失常。毒毛花苷G的正性肌力作用范围非常窄（约60 - 600 nM），心脏毒性刚好在此范围内重叠并迅速增加。固定浓度28 nM的扎莫特罗使异丙肾上腺素浓度 - 反应曲线右移，表明该药物具有竞争性β1肾上腺素能受体阻断作用。浓度为268 nM的毒毛花苷G与扎莫特罗在最大收缩性方面起相加作用，除最高浓度外未引起心肌耗氧量进一步增加，但在扎莫特罗浓度高于约20 nM时，结性心律略有增加。
