Negative inotropic influence of hyperosmotic solutions on cardiac muscle.
Negative inotropic influence of hyperosmotic solutions on cardiac muscle.
复制标题
高渗溶液对心肌的负性肌力影响。
DOI：
--
复制
发表时间：
1975
影响因子：
--
通讯作者：
J. Willerson
中科院分区：
文献类型：
--
作者：
K. Wildenthal;R. Adcock;J. S. Crie;G. Templeton;J. Willerson
在心肌中，生理或临床上遇到的中度高渗性（即，低于对照组200 mosM）特征性地发挥正性肌力作用，这可能是由结合肌钙蛋白的Ca 2+可用性增加介导的。相比之下，骨骼肌在暴露于高渗溶液时显示出显著的收缩抑制，即使是在轻度的高渗状态下。为了确定心肌中是否也存在类似的高渗性诱发抑郁的可能性，将猫的右心室乳头肌暴露于甘露醇或蔗糖的高渗溶液中，在这种情况下，通过预先暴露于4.0 mM Ca 2+的沐浴液和成对的电刺激来排除正性肌力作用，以在加入高渗物质之前使细胞内Ca 2+最大化。与其通常的正性肌力作用相反，在这些条件下的高渗溶液在所有测试的渗透压下引起心脏抑制。在50 mosM、100 mosM、150 mosM和200 mosM时，发育张力和最大发育速率（dT/dt）分别比对照组降低18%、30%、36%和42%（P均小于0.01）。达到峰值张力和静息张力的时间没有显著变化。当肌肉恢复到对照溶液时，张力发展也恢复正常。这些数据与以下假设一致：在测试范围内，所有程度的高渗透压对心肌产生显著的负性肌力影响，骨骼肌也是如此;这种张力增加效应的表现通常在低程度的高渗透压下会被掩盖，但是，骨骼肌中不存在压倒性的积极影响。
In cardiac muscle, moderate degrees of hyperosmolality of the type encountered physiologically or clinically (i.e., less than 200 mosM above control) characteristically exert a positive inotropic effect, which presumably is mediated by increased Ca2+ availability for binding to troponin. In contrast, skeletal muscle displays significant contractile depression on exposure to hyperosmotic solutions, even at mild degrees of hypertonicity. To determine whether a similar potential for hyperosmolarity-induced depression also exists in cardiac muscle, right ventricular papillary muscles from cats were exposed to hypertonic solutions of mannitol or sucrose under circumstances in which positive inotropic effects were precluded by prior exposure to a bathing solution of 4.0 mM Ca2+ and paired electrical stimulation to maximize intracellular Ca2+ before addition of the hyperosmotic substances. In contrast to their usual positive inotropic effects, hypertonic solutions under these conditions caused cardiac depression at all osmolarities tested. Developed tension and its maximal rate of development (dT/dt) decreased by 18% at 50 mosM above control, by 30% at 100 mosM, by 36% at 150 mosM, and by 42% at 200 mosM (P less than 0.01 for all). Time to peak tension and resting tension were not changed significantly. When the muscles were returned to control solutions, tension development also returned toward normal. The data are compatible with the hypothesis that, within the range tested, all degrees of hyperosmolarity exert a significant negative inotropic influence on cardiac muscle, as is true in skeletal muscle; manifestation of this effect of increased tonicity normally would be obscured at low degrees of hyperosmolality, however, by an overriding positive influence that is absent in skeletal muscle.