Outbred male rats were repeatedly injected IP with sub-lethal doses of lead acetate 3 times a week during 5 weeks. They developed an explicit, even if moderate, lead intoxication characterized by typical hematological and some other features. The next day after the last injection the heart of each animal was excised, and the trabecules and papillary muscles from the right ventricle were used for modeling in vitro isometric (with varying starting length of the preparation) regimes of the contraction-relaxation cycle with different preloads. Several well-established parameters of this model were found changed compared with the preparations taken from the hearts of healthy control rats. Background in vivo calcium treatment attenuated both systemic and cardiotoxic effects of lead to an extent. We show for the first time that subchronic intoxication with lead caused myocardial preparations in a wide range of lengths to respond by a decrease in the time and speed parameters of the isometric contraction while maintaining its amplitude and by a decrease in the passive stiffness of trabecules. The responses of the various heart structures are outlined, and the isomyosin ratio is shown to have shifted towards the slow isoform. Mechanistic and toxicological inferences from the results are discussed.

在5周内，每周一次将近致死的雄性大鼠IP注射亚致死剂量的乙酸铅3次，每周一次。他们表现出明显的，甚至中度的铅中毒，其特征是典型的血液学和其他一些特征。最后一次注射后的第二天，切除每只动物的心脏，并使用右心室的小梁和乳头肌对体外模拟的等距（制剂起始长度不同）方案进行收缩松弛周期的模拟。预载。与从健康对照大鼠心脏中提取的制剂相比，该模型的一些公认的参数被发现发生了变化。体内背景钙治疗在一定程度上减弱了铅的全身和心脏毒性作用。我们首次表明，铅引起的亚慢性中毒导致心肌准备在很宽的长度范围内，通过等轴测收缩的时间和速度参数的减少，同时保持其幅度和小梁的被动刚度的降低来做出响应。概述了各种心脏结构的反应，并且异肌球蛋白的比例已显示向缓慢的亚型转移。讨论了从结果得出的机理和毒理学推论。