Maruyama Y, Okayama H, Ishide N, Takishima T
Pflugers Arch. 1982 Oct;395(1):49-54. doi: 10.1007/BF00584967.
The effect of Ca antagonist on the contractile apparatus was investigated in glycerinated cardiac muscle preparations obtained from canine hearts. Each muscle preparation had three consecutive isometric contractions. The 1st and 3rd contractions were produced with a control contraction solution, and compared with the 2nd contraction which was induced with a contraction solution containing verapamil. The results showed that maximal developed tension (Po) was enhanced significantly by 1.02 X 10(-2) mM of verapamil, and the augmentation of contractility was dependent on the concentrations of verapamil. Thus, not only Po, but also dT/dt increased tremendously at 1.02 mM of verapamil. Such contractile potentiation by verapamil was also ascertained by another Ca antagonist, Diltiazem hydrochloride. The developed tension was maximum at pCa 4.0, and no developed tension was found at pCa 8.0. The relationship between pCa and tension with verapamil shifted to the left from that without verapamil, showing higher sensitivity to Ca2+. From these results, it was strongly indicated that Ca antagonist is a potentiating agent of the contractile force.
在从犬心脏获取的甘油化心肌制备物中研究了钙拮抗剂对收缩装置的作用。每个肌肉制备物进行三次连续的等长收缩。第一次和第三次收缩用对照收缩溶液产生，并与用含维拉帕米的收缩溶液诱导的第二次收缩进行比较。结果显示，1.02×10⁻² mM的维拉帕米显著增强了最大张力（Po），并且收缩性的增强取决于维拉帕米的浓度。因此，不仅Po，而且在1.02 mM维拉帕米时dT/dt也大幅增加。另一种钙拮抗剂盐酸地尔硫䓬也证实了维拉帕米的这种收缩增强作用。在pCa 4.0时张力最大，在pCa 8.0时未发现张力。有维拉帕米时pCa与张力之间的关系比没有维拉帕米时向左移动，表明对Ca²⁺具有更高的敏感性。从这些结果强烈表明，钙拮抗剂是收缩力的增强剂。
