Bloom S, Atlas D, Thompson J
Physiol Chem Phys. 1978;10(3):255-66.
Heavy water inhibition of skeletal muscle contraction in barnacle and frog is thought to occur through inhibition of Ca release by SR. If this were so, D2O might be useful for studies on control of the inotropic state in mammalian myocardium. We therefore compared selected properties of mechanically disaggregated leaky myocardial fragments, and actomyosin, in D2O and H2O. At equal values of electrode-determined acidity the contraction frequency, initial velocity of 45Ca uptake, and equilibrium (Ca)i/(Ca)o of the myocardial fragments were all less when heavy water was used. For each of these parameters, and for actomyosin superprecipitation, the H2O and D2O acidity-response curves were similar but the D2O curve was shifted to the right. The actomyosin sedimentation rate was less in D2O than in H2O at near neutral acidity but not different under more acidic or basic conditions. Actomyosin ATPase showed an acidity-dependent increased activity in D2O. These results verify that heavy water inhibits contraction in mammalian myocardium, as is the case with invertebrate and frog skeletal muscle. The effect, however, cannot be attributed to inhibition of Ca release from SR.
人们认为，重水对藤壶和青蛙骨骼肌收缩的抑制作用是通过抑制肌浆网（SR）释放钙来实现的。如果真是这样，重水可能有助于研究哺乳动物心肌收缩力状态的控制。因此，我们比较了在重水和普通水中机械分离的有渗漏的心肌碎片以及肌动球蛋白的某些特性。在电极测定的酸度值相等时，使用重水时心肌碎片的收缩频率、45Ca摄取的初始速度以及细胞内钙浓度与细胞外钙浓度的平衡比值均较低。对于这些参数中的每一个以及肌动球蛋白的超沉淀，普通水和重水的酸度响应曲线相似，但重水曲线向右移动。在接近中性酸度时，重水中肌动球蛋白的沉降速率低于普通水，但在酸性或碱性更强的条件下没有差异。重水中肌动球蛋白ATP酶的活性呈现出酸度依赖性增加。这些结果证实，重水会抑制哺乳动物心肌的收缩，就像对无脊椎动物和青蛙骨骼肌的作用一样。然而，这种作用不能归因于对肌浆网释放钙的抑制。
