Eric G. Ball

Studies on the metabolism of adipose tissue— XVIII. In vitro effects of insulin, epinephrine and glucagon on lipolysis and glycolysis in pigeon adipose tissue

Abstract 1. 1. Lipolysis in pigeon adipose tissue in vitro was stimulated by epinephrine and glucagon. 2. 2. Tissue from males was less sensitive to glucagon than that from females. 3. 3. Stimulation of lipolysis did not occur anaerobically. 4. 4. The molar ratio of FFA to glycerol produced under hormone stimulation was three to four and was not altered by the presence of glucose even though considerable glucose consumption did occur. 5. 5. Lack of re-esterification of FFA and the possible accumulation of mono- and diglycerides is suggested. 6. 6. Both epinephrine and glucagon stimulated lactate production in the presence of glucose. 7. 7. A significant increase in O 2 consumption was seen only when both epinephrine and glucose were present. Insulin had no observable effect on lipolysis or glycolysis.

Inhibition of lipolytic processes in rat adipose tissue by antimalarial drugs

Abstract Lipolytic processes in vitro of rat epididymal fat pads are inhibited by the antimalarial drugs quinine, quinidine, quinacrine, chloroquine, hydroxychloroquine and primaquine. These compounds inhibit hormone activated lipolysis, the lipolytic activity of adipose tissue homogenates and the activity released into the medium by heparin.

METABOLIC STUDIES ON THE GAS GLAND OF THE SWIM BLADDER

1. Metabolic studies have been carried out on the gas gland of the swim bladder of the scup, Stenotomus chrysops, at 30° C.2. The intact gland has a Qo2 = 2.0 which is not appreciably altered by the addition of glucose. Homogenates of the gland have a much lower rate of oxygen consumption.3. The intact gland converts glucose to lactic acid at a rapid rate. This conversion has been followed by measurement of glucose disappearance, lactic acid appearance and the release of CO2 from a bicarbonate medium. Values of QCO2NN2 ranging from 12-23 have been found. Lactic acid appearance accounts for 70-90% of the glucose that disappears. The gland does not show a Pasteur effect since similar values are obtained under either aerobic or anaerobic conditions.4. The rate of anaerobic glycolysis is greatest at an alkaline pH and is markedly influenced by the cation composition of the medium. Activities in an all-sodium medium are 3-4 times those in an all-potassium medium.5. A schematic diagram of the possible role of l...

Quantitative aspects of brown adipose tissue thermogenesis during arousal from hibernation.

The in vitro respiratory rates of brown adipose, heart, and liver tissues were studied in the bat (Eptesicus fuscus) to determine their contribution to the heat necessary for arousal from hibernation. The mean oxygen consumption of the whole animal for arousal from hibernation was 66.2 ml. of which 5.7% is estimated to be utilized by brown adipose tissue, and 1.2% by heart and liver combined. The maximum respiratory rate of brown adipose tissue when stimulated by epinephrine was 134 µl. O2/l00 mg. fresh tissue/hr. Despite this high in vitro respiratory rate, it seems inadequate, on the basis of other evidence, to account for the heat production expected for brown adipose tissue during arousal from hibernation. A thermogram of a bat arousing from hibernation is presented which provides pictorial evidence of the large thermogenic capacity of brown adipose tissue. It is concluded that the conditions necessary to measure the maximum respiratory rate of brown adipose tissue, such as it occurs during arousal fr...

Factors affecting lipolysis rates in rat adipose tissue

Abstract An attempt has been made to elucidate the mechanism in rat adipose tissue by which glucose overcomes the antilipolytic action of insulin and enhances lipolysis induced by epinephrine. The possible role in this phenomenon of the insulin-activated cell membrane carrier system for glucose has been examined by studying the action of other transportable sugars. Fructose behaves like glucose but higher concentrations are needed for maximum effects. No action is shown by 3- O -methyl glucose and, 2-deoxyglucose displays antilipolytic actions of its own. An antilipolytic action of insulin is seen when lipolysis is induced by theophylline, but not when dibutyryl cyclic AMP is employed. In both cases, however, an enhanced rate of lipolysis is observed if glucose and insulin are present. In each of these situations the accumulation of free fatty acids in the tissue is high and remains unchanged in the presence of glucose. Thus the enhancement of lipolysis by glucose would not appear to be dependent solely upon its ability to furnish glycerophosphate for reesterification of free fatty acids. Involvement of glycerophosphate in some manner is suggested, however, by the fact that lactate, inactive by itself, is able to significantly augment the stimulatory action of glucose upon lipolysis. A variety of substances including glycerophosphate, which could be produced by the metabolism of glucose or result from the fatty acid reesterification process were tested for their effects upon lipolysis without success.

The composition of the mitochondrial membrane in relation to its structure and function.

Publisher Summary Mitochondria are considered the power house of the cell. The conversion of fatty acids to acetyl CoA occurs in mitochondria. It also localizes the complex enzyme system that transmits to oxygen the electrons removed from all the various metabolic substrates and converts part of the energy so released into the form of high energy phosphate. This chapter reviews the evidence that indicates that this enzyme system is embedded in the membranes of the mitochondria. It also discusses the composition, structure, and function of this membrane. Ball and Coopers method for mitochondrial membrane preparation includes (1) removing soluble components, (2) differentially suspending particles, (3) precipitating particles with (NH 4 ) 2 SO 4 , (4) suspending particles, and (5) precipitating and resuspending particles. The pellet obtained by high speed centrifugation in the last step of the preparation is fixed in osmic acid. This pellet is composed of thin-walled membranous, vesicular structures. The fact that the lipid components of the membrane preparation can be extracted by the use of cold chloroform–methanol indicates that they are not bound to the protein components by covalent linkages.

Studies on the metabolism of adipose tissue. VII. A comparison of the effects of insulin and a growth-hormone preparation on oxygen consumption in bicarbonate and phosphate buffers.

Abstract Simultaneous measurements of the oxygen consumption of rat epididymal adipose tissue in Krebs-Ringer bicarbonate and phosphate buffers have been made using the Warburg reprirometer and a specially-constructed oxygen-electrode apparatus. Experiments performed by incubating one tissue in phosphate buffer in a Warburg vessel and a paired tissue from the same animal in bicarbonate buffer in the electrode tissue chamber have indicated that the oxygen uptake of the untreated tissue is not affected by the buffer composition. Glucose, 3 mg/ml, was employed in both media. When a sheep growth-hormone preparation was added to the incubation media so as to give a final concentration of 0.093 mg/ml the oxygen consumption of the tissue was approximately doubled irrespective of the buffer employed. The addition of insulin (0.1 unit/ml), however, produced a stimulation of oxygen uptake only in bicarbonate buffer and this effect was dependent upon the presence of glucose in the medium. When both hormones (growth-hormone preparation, 0.045 mg/ml; insulin, 0.1 unit/ml) were added simultaneously, the response of the tissue was much larger than when only the growth-hormone preparation was added, although the response remained the same in each buffer.

ENERGY RELATIONSHIPS OF THE OXIDATIVE ENZYMES

Life, from the viewpoint of the physical chemist, may be defined as a manifestation of the transformation of energy by the living organism. The plant, for example, through the agency of chlorophyll, is able to transform solar energy into potential chemical energy by the synthesis from CO, and water of carbohydrates, fats, and proteins. The animal, on the other hand, is able to release this stored solar energy by converting these plant products back again into COz and water. It is, of course, by this procedure, which we term metabolism, that the animal obtains the energy by which he moves himself and surrounding objects, by which he maintains a body temperature usually higher than his environment, and by which he performs a multitude of processes whose study is the delight of the physiologist and which constitute life. During the past twenty years, our knowledge of the metabolic processes whereby carbohydrates, fats, and proteins undergo degradation in the animal body has increased greatly. To be sure, we are still far from a complete understanding of the processes involved, but we have advanced far enough so that probing fingers are already beginning to search for the mechanism whereby this energy release is geared to perform the functions essential to life. Let us, therefore, consider briefly what we know today concerning the oxidative reactions by which foodstuffs are converted into CO, and water and see what deductions we may draw concerning the amount of energy thereby released and its utilization by the living cell. In the consideration of the energy release of foodstuffs during oxidation, i t has been the custom to write an over-all equation for the reaction such as the one shown here for glucose:

HEMOLYTIC ACTION OF SILVER OCCURRING AS AN IMPURITY IN CHEMICALLY PURE SODIUM CHLORIDE

1. The hemolysis of fish erythrocytes by isotonic solutions made from certain brands of sodium chloride has been shown with the aid of the spectrograph to be due to silver occurring as an impurity in those salts.2. The amount of silver present in such salts is of the order of magnitude of 10-3 to 10-4 per cent and originates from the use of silverlined vessels in the purification process.3. A simple procedure for the removal of silver from such salts by adsorption on charcoal has been described.4. Palladium is the only other element that has been found to be as effective as silver in causing hemolysis.5. Since the toxic action of silver is not limited to the hemolysis of fish erythrocytes, it is suggested that silver-free sodium chloride be used in the preparation of physiological saline solutions.

Studies on the metabolism of adipose tissue. VIII. Alterations produced by biotin deficiency in the rat

Abstract A comparison of the metabolism of glucose in vitro by adipose tissue from normal, biotin-deficient, and biotin-restored rats has been made. Insulin enhances the uptake of glucose by tissue from all three types of animals. In the biotin-deficient animal, 41% of the glucose is converted to lactic acid as compared to 7% in the normal. A corresponding decrease in the net CO 2 production is observed in the biotin-deficient animal signifying a lowered fatty acid synthesis. A single injection of 300 μg. biotin results in a rapid restoration of the metabolic pattern toward the normal.