Myocardial function and energy metabolism in carnitine-deficient rats

Carnitine is essential for mitochondrial metabolism of long-chain fatty acids and thus for myocardial energy production. Accordingly, carnitine deficiency can be associated with cardiomyopathy. To better understand this disease, we determined myocardial function and energy metabolism in a rat model of carnitine deficiency. Carnitine deficiency was induced by a 3- or 6-week diet containing N-trimethyl-hydrazine-3-propionate, reducing cardiac and plasma carnitine by 70-85%. Myocardial function was investigated in isolated isovolumic heart preparations. Carnitine-deficient hearts showed left ventricular systolic dysfunction, reduced contractile reserve, and a blunted frequency-force relationship independently of the substrate used (glucose or palmitate). After glycogen depletion, palmitate could not sustain myocardial function. Histology and activities of carnitine palmitoyl transferase, citrate synthase, and cytochrome c oxidase were unaltered. Thus, as little as 3-6 weeks of systemic carnitine deficiency can lead to abnormalities in myocardial function. These abnormalities are masked by endogenous glycogen and are not accompanied by structural alterations of the myocardium or by altered activities of important mitochondrial enzymes.     

Myocardial concentrations of high energy phosphates in normal mini-pigs and dogs

Zusammenfassung Die Gewebskonzentrationen an ATP, ADP, ATP+ADP, Kreatinphosphat, Kreatin und Kreatinphosphat + Kreatin sind unter vergleichbaren Bedingungen im linken Ventrikel von Mini-pig-Herzen kleiner als im Hundeherzen. Die Unterschiede in den Koeffizienten (ATP/ADP und Kreatinphosphat/Kreatin) dürfen narkosebedingt sein. Sämtliche Messgrössen sind nicht mit dem Entnahmeort der Biopsien (apikal, basal) korreliert.

---

---

Supported by the Swiss National Science Foundation (Grant Nr. 3.484).     

Adenine nucleotide metabolism during anoxia and postanoxic recovery in insects

Severe hypoxia (anoxia), if maintained for more than a few minutes, causes irreversible damage in humans and other mammals. Why mammals are so vulnerable to anoxia is not fully understood. It is therefore of interest to study animals that are more tolerant of anoxia in order to identify physiological and metabolic properties that are correlated with a high tolerance of anoxia. Insects have high metabolic rates and their energy metabolism is dependent on aerobic ATP production. In insects, as in mammals, anoxia causes a rapid breakdown of physiological function, resulting in a state similar to rigor mortis. This is accompanied by a precipitous decrease in metabolic rate. In contrast to mammals, however, insects can survive anoxia for many hours and recover spontaneously and completely when air is again available. We have followed the metabolism of adenine nucleotides in locust tissues (mainly in the flight muscle) over 3 h of anoxia and during recovery from 1 h of anoxia. The content of ATP in the flight muscle dropped to 1% of normal during 2 h of anoxia. The main product was AMP which increased in content more than 20-fold. Some of the AMP was deaminated to IMP and this was further dephosphorylated to inosine. Altogether less than 30% of the total adenine nucleotides were degraded during 3 h of anoxia and this may contribute to the amazing ability of insects to recover from prolonged anoxia.     

An evidence for decrease of energy production in thiamine deficient failing rat heart

Résumé La combinaison des substrats — acides pyruvique et fumarique — inhibent le gonflement de mitochondries isolées du coeur de rat, en accord avec le maintien de l'intégrité de la structure mitochondriale par l'adénosine triphosphate produite. On constate la diminution successive de cette inhibition dans des rats déficients en thiamine, par suite du blocage au niveau de la décarboxylation pyruvique. De plus cette carence vitaminique provoque une décroissance graduelle du nombre des mitochondries dans le tissu cardiaque.

---

---

Supported by the Grants H-4012 from the National Heart Institute and K62-3 from the Hospital Division, U.S. Public Health Service. We thank MissV. Meyer for the heart size deteminations.     

Hepatic protein turnover in goldthioglucose-induced obesity

Summary Goldthioglucose obese mice fail to regulate hepatic protein turnover in response to variable energy intake in contrast to lean mice.     

Phloridzin and red cell phosphate turnover

Résumé L'addition de phlorizine ou de phlorétine à une suspension d'hématies humaines ralentit l'allure d'incorporation du radio-phosphate dans les cellules. Celles-ci contiennent les mêmes quantités d'esters phosphoriques après l'action de la phlorizine. Les deux drogues ne modifient pas non plus les concentrations en Na et en K des cellules.     

Effects of anoxia on excitability,refractoriness, and contractility in isolated rabbit atria

Zusammenfassung An der isolierten Kaninchenherzvorkammer verursacht Sauerstoffmangel Verminderung der diastolischen Erregbarkeit, Verlängerung der refraktären Phase sowie Herabsetzung der Kontraktionsfähigkeit. Herzmuskelflimmern wurde während dieser Anoxie nicht beobachtet. Sauerstoffzufuhr führte zu einer vollständigen Aufhebung der Anoxieauswirkung auf die absolute Refraktärperiode, zu einer teilweisen Aufhebung dieser Auswirkungen auf die Dauer der refraktären Gesamtpause, die diastolische Erregbarkeit und das Kontraktionsvermögen.     

The turnover of F-actin-bound ADP in vivo

Summary A procedure for estimating the rate of turnover of F-actin-bound ADP in vivo is described. A turnover rate of 0.88 h^–1 was determined for mouse muscle F-actin. The validity of the method when used to estimate the turnover rate of F-actin per se is discussed in relation to the possible exchange of F-actin-bound ADP.Acknowledgments. The invaluable technical assistance of Mr L. Carrington is gratefully acknowledged.     

Demonstration of neurofibrillary degeneration induced by anoxia in spinal motor neurons in vitro

Zusammenfassung Die neurofibrilläre Degeneration durch Anoxie wurde an Nervenzellen des Rückenmarks von Hühnerembryonen mit der Bodian-Silberimprägnation in Gewebekultur studiert.     

Thiamine triphosphate metabolism and its turnover in the rat liver

Summary When rats were injected with a thiamine disulfide derivative, the content of thiamine triphosphate (TTP) in the liver doubled within 3 h after a preceeding rise in thiamine pyrophosphate; it then returned to the basal level within the next 3h, indicating a net increase of TTP in vivo and its rapid turnover.     

Response of neuronal lysosomes to anoxia in tissue culture of mammalian cerebellum

Zusammenfassung In Gewebekulturen wurde die zytochemische Veränderung der Lysosomen durch Sauerstoffentzug an Säugetierkleinhirnnervenzellen mit der Gomori-Säurephosphatasemethode studiert.     

能源互联网与能源路由器

日益紧张的能源供需矛盾和环境压力等要求可再生清洁能源应该在未来能源体系中承担主要能源供给任务.能源传输技术、存储技术、信息通信以及高性能计算技术的发展为有效利用分布式、间歇性可再生能源提供了技术支持.针对类似于信息互联网式的能源互联网愿景,本文探讨了以能源路由器为核心交换装置的能源互联网实现模型,从能源路由器的实现目标,已有支撑技术和实现部署方式等方面分析了涉及的关键技术,并结合已有研究成果说明了该领域亟需突破的研究方向.     

The turnover of F-actin-bound ADP in vivo.

A procedure for estimating the rate of turnover of F-actin-bound ADP in vivo is described. A turnover rate of 0.88 h-1 was determined for mouse muscle F-actin. The validity of the method when used to estimate the turnover rate of F-actin per se is discussed in relation to the possible exchange of F-actin-bound ADP.     

Mitotic force generators and chromosome segregation

The mitotic spindle uses dynamic microtubules and mitotic motors to generate the pico-Newton scale forces that are needed to drive the mitotic movements that underlie chromosome capture, alignment and segregation. Here, we consider the biophysical and molecular basis of force-generation for chromosome movements in the spindle, and, with reference to the Drosophila embryo mitotic spindle, we briefly discuss how mathematical modeling can complement experimental analysis to illuminate the mechanisms of chromosome-to-pole motility during anaphase A and spindle elongation during anaphase B.     

Different response of adenine nucleotide synthesis de novo in kidney and brain during aerobic recovery from anoxia and ischemia

Zusammenfassung Unter Verwendung von¹⁴C-markiertem Glycin wurden durch Bestimmung der mittleren spezifischen Aktivitäten von Glycin im Gewebe und durch Messung der Glycin-Inkorporation in die Adenin-Nucleotide die de novo-Syntheseraten dieser Verbindungen in Niere und Gehirn in vitro und in vivo unter normoxischen Bedingungen sowie nach vorausgegangener Anoxie bzw. Ischämie bestimmt. Zwischen der Fähigkeit eines Organs zur postanoxischen Nukleotidsynthese-Steigerung und seiner funktionellen Erholungsfähigkeit nach Sauerstoffmangel scheinen enge Beziehungen zu bestehen.

---

---

Fellow of the A.-v.-Humboldt-Stiftung.

---

This work was supported by a grant from the Deutsche Forschungsgemeinschaft No. Ge 129/7.     

Electrically-induced mechanical activity of the isolated guinea-pig sciatic nerve. Influences of calcium and anoxia

Summary The electrically induced motility of isolated segments of guinea-pig sciatic nerves is reported. This motility was characterized by waves of tensional variations. The removal of Ca²⁺ from the suspending solution, the addition of EDTA as well as anoxia, resulted in a decrement of tension accompanied by a prolongued duration of the cycles of mechanical activity.This work was supported by grant 6638, from the Consejo Nacional de Investigaciones Cientificas y Técnicas de la República Argentina (C.O.N.I.C.E.T.).     

Differences in the content and turnover of noradrenaline in rat heart atria and ventricles and circadian-phase-dependency

In light-dark-synchronized male rats the levels of noradrenaline in heart atria were about 3 times that found in heart ventricles. Noradrenaline turnover rate which were about 8-9 fold greater for the atria than for the ventricles displayed a circadian-phase-dependency with increased rates in the dark period in both parts of the rat heart.     

The effect of hypoxia on hepatic cytochromes and heme turnover in rats in vivo

Summary We evaluated the effect of hypoxia (7% v/v) on hepatic heme turnover in vivo and microsomal heme protein content in male Sprague-Dawley rats. Hepatic heme protein turnover, measured as¹⁴CO-production during continuous infusion of 5-¹⁴C-aminolevulinic acid, a precursor of nonerythrogenic heme, was decreased 60% during hypoxia and returned to control levels promptly after reoxygenation. Hepatic cytochrome P-450 content was decreased in hypoxic and 24-h reoxygenated animals. We conclude that normobaric hypoxia decreases hepatic cytochrome P-450 which could contribute to decreased drug metabolism in hypoxia. This decrease is probably due to heme oxygenase-independent breakdown of hepatic heme.     

The effect of hypoxia on hepatic cytochromes and heme turnover in rats in vivo

We evaluated the effect of hypoxia (7% v/v) on hepatic heme turnover in vivo and microsomal heme protein content in male Sprague-Dawley rats. Hepatic heme protein turnover, measured as 14CO-production during continuous infusion of 5-14C-aminolevulinic acid, a precursor of nonerythrogenic heme, was decreased 60% during hypoxia and returned to control levels promptly after reoxygenation. Hepatic cytochrome P-450 content was decreased in hypoxic and 24-h reoxygenated animals. We conclude that normobaric hypoxia decreases hepatic cytochrome P-450 which could contribute to decreased drug metabolism in hypoxia. This decrease is probably due to heme oxygenase-independent breakdown of hepatic heme.