Ion Gradients And Metabolic Energy In Animal Tissue

Alcohol Abuse And Alcoholism

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Abstract

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 (Masuda T et al, J Biol Chem 1990;265:20321-34). The metabolism of ethanol increases the resting electrical potential of hepatocytes from 28 to 40 mV (Veech RL et al, Alcoholism Clin Exp Res 1994;18:1040-56). Previously, we showed that merely changing the substrate available altered the DG of ATP hydrolysis in heart (Kashiwaya Y et al, Am J Cardiol 1997;80:50A- 64A). 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 published (Veech, R.L. et al, IUBMB Life, 54: 241-252, 2002). 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 and findings have been published (Liberthal, W. et al, Shock, 17: 61-69, 2002). 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 hemmorhage. 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. 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. This manuscript has now been published (Wilcox, J.P. et al, J. Biol. Chem. 277: 49911-20, 2002). Resuscitation fluids used for routine surgery, resuscitation from hemorrhage and burns have been unaltered for 50 years. The standard high volume fluid is Ringer!|s lactate, which contains 26 mM D,L-lactate, although recently some has appeared containing only L-lactate. It has been repeatedly shown that the metabolism of d-lactate produces untoward consequences including encephalopy, cardiac arrythmias (26) and apoptosis in the lung after hemorrhage (27). So called Da Nang lung was a major cause of morbidity and mortality during treatment of hemorrhage in the Viet Nam war. Accordingly, a new family where Na D,L-lactate is being replaced with Na D-fO-hydroxybutyrate has been prepared and is being tested in a number of animal models of hemorrhage and examining effects in lung, kidney and heart. More recently, studies done in Boston in a hemorrhage model in rat has shown that adimistration of Ringer's ketone solution decreases mortality in the rat when compared to either standard Ringer's lactate, 0.9% sodium chloride or glucose, K+ and insulin. This work has been supported by funds provided by the DoD and more recently, in response to a solicitation from DARPA, a request for funds from has been submitted in collaboration with Dr. Robert Valeri of the Naval Blood Research Laboratory. If successful, this program will progress to clinical trials of these new fluids. A decision is expected in October, 2004.