Silva Marito A S C, de Oliveira Thiago F, Almenara Camila C P, Broseghini-Filho Gilson B, Vassallo Dalton V, Padilha Alessandra S, Silveira Edna A
Department of Physiological Sciences, Federal University of Espirito Santo, CCS/UFES. Av. Marechal Campos, 1468, Maruípe, 29043-090, Vitoria, Brazil.
Biol Trace Elem Res. 2015 Oct;167(2):280-7. doi: 10.1007/s12011-015-0300-0. Epub 2015 Mar 21.
Lead exposure has been considered to be a risk factor for hypertension and cardiovascular disease. Our purpose was to evaluate the effects of low plasma lead concentration on cardiac contractility in isolated papillary muscles. Wistar rats were divided in control group or group treated with 100 ppm of lead acetate in the drinking water for 15 days. Blood pressure (BP) was measured weekly. At the end of the treatment period, the animals were anesthetized and euthanized, and parameters related to isolated papillary muscle contractility were recorded. The lead concentrations in the blood reached 12.3 ± 2 μg/dL. The BP was increased in the group treated with 100 ppm of lead acetate. Lead treatment did not alter force and time derivatives of the force of left ventricular papillary muscles. In addition, the inotropic response induced by an increase in the extracellular Ca(2+) concentration was reduced in the Pb(2+) group. However, the uptake of Ca(2+) by the sarcoplasmic reticulum and the protein expression of SERCA and phospholamban remained unchanged. Postrest contraction was similar in the both groups, and tetanic peak and plateau tension were reduced in lead group. These results demonstrated that the reduction in the inotropic response to calcium does not appear to be caused by changes in the trans-sarcolemmal calcium flux but suggest that an impairment of the contractile machinery might be taking place. Our results demonstrate that even at a concentration below the limit considered to be safe, lead exerts deleterious effects on the cardiac contractile machinery.
铅暴露一直被认为是高血压和心血管疾病的一个风险因素。我们的目的是评估低血浆铅浓度对离体乳头肌心脏收缩力的影响。将Wistar大鼠分为对照组或饮用含100 ppm醋酸铅的水15天的处理组。每周测量血压（BP）。在治疗期结束时，将动物麻醉并处死，并记录与离体乳头肌收缩力相关的参数。血液中的铅浓度达到12.3±2μg/dL。用100 ppm醋酸铅处理的组血压升高。铅处理未改变左心室乳头肌的力和力的时间导数。此外，在Pb(2+)组中，细胞外Ca(2+)浓度升高引起的变力反应降低。然而，肌浆网对Ca(2+)的摄取以及SERCA和受磷蛋白的蛋白表达保持不变。两组的静息后收缩相似，铅组的强直峰和平台期张力降低。这些结果表明，对钙的变力反应降低似乎不是由跨肌膜钙通量的变化引起的，而是表明收缩机制可能正在受损。我们的结果表明，即使在低于被认为是安全的浓度下，铅也会对心脏收缩机制产生有害影响。
