Ion Gradients And Metabolic Energy In Animal Tissue

工作灌流心脏中9种主要无机离子的梯度能量、胞外相和胞内相之间的电势以及ATP水解物的DG接近平衡。乙醇的代谢使肝细胞的静息电位从28 mV增加到40 mV。在此之前，我们发现仅仅改变可用底物就会改变心脏中ATP水解酶的DG。由于任何类型的损伤都会引起细胞离子分布的典型变化，即细胞获得Na+、失去K+和肿胀，这些典型的损伤变化可能会被损伤或烧伤患者所用液体成分的简单改变所逆转。由于这些研究和我们向医学学会召集的一个小组提出的建议，建议开始调查制造新的复苏液体的可行性(见：液体复苏，治疗战斗伤亡和平民受伤的科学状况，国家科学院出版社，1999年)。目标是提高出血和烧伤的标准治疗，这在过去50年里没有改变。我们正在与海军血液研究实验室合作进行这项工作。我们的手稿将ATP水解的G增量与所有9种常见无机离子在心、肝和红细胞的胞外相和胞内相之间的能量梯度联系在一起，现在已经被接受出版。这些组织的电势从-86到-28到-6 mV不等。我们发现Na+梯度的能量约为ATP水解能的1/3，用KCl微电极测得的静止膜电位是电泳膜中最重要的离子所需的功函数。因此，离子梯度体系似乎是一个依赖于ATP水解能量的Gibbs Donnan近平衡体系。这导致了一系列新的肠外液体的制备和测试，这些液体用于出血、复苏、头部创伤、中风和军事和民用环境中的烧伤治疗。在军事环境中，所有致命创伤中有一半是头部创伤造成的。因此，我们设计了新的液体来治疗与出血相关的头部创伤。与海军研究办公室合作，目前正在全国四个不同实验室的动物模型中对这些新液体进行评估，以确定这些新液体是否可以降低发病率和死亡率。此外，我们与海军血液研究实验室和约翰霍普金斯大学重症监护医学部合作，开发了用于治疗大脑中动脉两小时闭塞的新液体。这些新的治疗方法将在来年与现有的治疗方法进行比较，以确定新的液体是否减少了大脑中动脉闭塞引起的短暂性脑缺血后的细胞死亡和凋亡。最后，我们与牛津BHF核磁共振实验室合作，通过测定镰状细胞性贫血患者红细胞中的游离[Mg2+]，继续并扩展了我们在测定游离[Mg2+]方面的工作。服用镁曾被认为是治疗镰刀危机的一种方法。我们在本文中指出，以前关于游离[Mg~(2+)]水平升高的报道是不正确的，这是由于ATP的丢失导致Mg~(2+)结合减少。这些观察结果对确定镰刀危象的适当治疗方法有价值。

The energy of the gradients of the nine major inorganic ions in working perfused heart are in near equilibrium with each other, the electrical potential between extra- and intracellular phase and the DG of ATP hydrolysis. The metabolism of ethanol increases the resting electrical potential of hepatocytes from 28 to 40 mV. Previously, we showed that merely changing the substrate available altered the DG of ATP hydrolysis in heart. Since injuries of any sort induce a stereotypic change in cellular ionic distributions wherein the cell gains Na+, loses K+ and swells, these stereotypic changes of injury can possibly be reversed by simple changes in the compositions of fluids administered to victims of injury or burns. As a result of these studies and our suggestions to a panel convened by the Academy of Medicine, a recommendation has been made that investigation of the feasibility of making new resuscitation fluids be initiated (see: Fluid Resuscitation, state of the science for treating combat casualties and civilian injuries, National Academy Press, 1999). The goal is to improve the standard treatment of hemorrhage and burns, which has not changed over the past 50 years. We are collaborating in this effort with the Naval Blood Research Lab. Our manuscript relating the Delta G of ATP hydrolysis to the energy of the gradients of all 9 common inorganic ions between extra and intracellular phases of heart, liver and red blood cell has now been accepted for publication. These tissues differ in electrical potential from -86 to -28 to -6 mV. We found that the energy of the Na+ gradient was about 1/3 of the energy of ATP hydrolysis and that the resting membrane potential as measured by KCl microelectrodes was a work function required to electrophoresis the most permeant ion. The system of ion gradients therefore appears to be a Gibbs Donnan near-equilibrium system dependent upon the energy of ATP hydrolysis. This has led to the preparation and testing of a new family of parenteral fluids for use in hemorrhage, resuscitation, head trauma, stroke and the treatment of burns in both military and civilian settings. In military settings, half of all fatal wounds are the result of head trauma. Accordingly, we have designed new fluids for the treatment of head trauma associated with hemorhage. In collaboration with the Office of Naval Research, these new fluids are currently being evaluated in animal models in four different laboratories across the country to determine if these new fluid decrease morbidity and mortality. In addition, in collaboration with the Naval Blood Research Laboratory and the Dept of Critical Care Medicine at Johns Hopkins, we have developed new fluids for the treatment of two hour occlusion of the middle cerebral artery. These new treatments will be compared with existing treatments over the course of the coming year to determine if the new fluids decrease the cell death and apoptosis following transient ischemia induced by occlusion of the middle cerebral artery. Finally, we have continued and extended our work on the determination of free [Mg2+], in collaboration with the BHF NMR laboratory in Oxford by determining the free [Mg2+] in red cells from patients with sickle cell anemia. Administration of Mg had been proposed as a therapy for sickle crisis. We showed in this paper, that previous reports of the levels of free [Mg2+] being elevated were incorrect due to loss of ATP with result decrease in Mg2+ binding. These observations should be of value in determining appropriate therapy in sickle crisis.