de Morais H S, Muir W W
Departamento de Clínicas Veterinárias, Universidade Estadual de Londrina, Paraná, Brazil.
Vet Surg. 1995 Jul-Aug;24(4):356-64. doi: 10.1111/j.1532-950x.1995.tb01343.x.
The effects of medetomidine on load-dependent and relatively load-independent indices of left ventricular contractility and hemodynamics were studied in 8 chloralose-anesthetized, autonomic-blocked dogs. Left ventricular contractility was assessed by the maximum rate of increase in pressure (dP/dtmax), the slope of the end-systolic pressure volume relationship (Ees), preload recruitable stroke work (PRSW), and dP/dtmax-end-diastolic volume relation (SdPV). Dogs received 5 or 10 micrograms/kg of medetomidine IV. The dP/dtmax decreased significantly 30 minutes after both doses of medetomidine. The Ees did not change. Both SdPV and PRSW increased 5 minutes after both doses of medetomidine. Mean arterial pressure, left-ventricular end-diastolic and end-systolic pressures, peripheral vascular resistance and effective arterial elastance increased 5 minutes after both doses of medetomidine. Stroke volume, cardiac output, and stroke work decreased 5 minutes after medetomidine administration. End-diastolic volume did not change. End-systolic volume increased but the difference was not significant. Our study suggests that medetomidine increases inotropy and vascular resistance in autonomic-blocked dogs and that both ventricular and vascular responses to pharmacological manipulation must be considered for a complete assessment of the inotropic effects of a drug.
在8只经氯醛糖麻醉、自主神经阻断的犬中，研究了美托咪定对左心室收缩力和血流动力学的负荷依赖性及相对负荷非依赖性指标的影响。通过压力最大上升速率（dP/dtmax）、收缩末期压力-容积关系斜率（Ees）、前负荷可募集搏功（PRSW）以及dP/dtmax-舒张末期容积关系（SdPV）来评估左心室收缩力。犬静脉注射5或10微克/千克的美托咪定。给予两种剂量美托咪定后30分钟，dP/dtmax均显著降低。Ees未改变。给予两种剂量美托咪定后5分钟，SdPV和PRSW均增加。给予两种剂量美托咪定后5分钟，平均动脉压、左心室舒张末期和收缩末期压力、外周血管阻力以及有效动脉弹性均增加。给药后5分钟，搏出量、心输出量和搏功降低。舒张末期容积未改变。收缩末期容积增加，但差异不显著。我们的研究表明，美托咪定可增加自主神经阻断犬的心肌收缩力和血管阻力，并且为了全面评估药物的变力作用，必须同时考虑心室和血管对药物干预的反应。
