scholarly journals Microcalorimetric measurements of heat production in brown adipocytes from control and cafeteria-fed rats

1986 ◽  
Vol 235 (2) ◽  
pp. 337-342 ◽  
Author(s):  
D G Clark ◽  
M Brinkman ◽  
S D Neville
Keyword(s):  
Oleic Acid ◽  
Heat Production ◽  
Oxidative Metabolism ◽  
Heat Output ◽  
O2 Consumption ◽  
O2 Uptake ◽  
Average Volume ◽  
Brown Adipocytes ◽  
Chemical Agents ◽  
Sequential Addition

The effects of the sequential addition of glucose, noradrenaline, propranolol and oleic acid on the rates of O2 consumption and heat production by isolated interscapular brown adipocytes from control and cafeteria-fed rats were compared. Although the chemical agents produced very similar changes in oxidative metabolism, the actual rates of O2 uptake and heat output in adipocytes from the cafeteria-fed rats, when expressed per g dry wt. of cells, were approx. 65% less than those obtained with cells from the control rats. However, when the same results were expressed per 10(8) multiloccular brown adipocytes, rather than gravimetrically, rates of O2 consumption and heat production were equivalent. Further interpretation of these data is complicated, because the average volume of multiloccular brown adipocytes from cafeteria-fed rats was 2.5 times that for multiloccular cells from control animals.

scholarly journals Effects of fructose concentration on carbohydrate metabolism, heat production and substrate cycling in isolated rat hepatocytes

1979 ◽  
Vol 184 (3) ◽  
pp. 501-507 ◽  
Author(s):  
Dallas G. Clark ◽  
Owen H. Filsell ◽  
David L. Topping
Keyword(s):  
Heat Production ◽  
Rat Hepatocytes ◽  
Fold Increase ◽  
Hepatic Metabolism ◽  
Heat Output ◽  
O2 Consumption ◽  
O2 Uptake ◽  
Isolated Rat Hepatocytes ◽  
High Concentrations ◽  
Fructose 1,6 Bisphosphate

1. Hepatocytes from starved rats were incubated with 5mm-glucose, labelled uniformly with 14C and specifically with 3H at positions 1, 2, 3 or 6, and with fructose at concentrations of 2.5, 7.5 or 25mm. 2. In the absence of other substrates only 1% of the radioactivity initially present in [U-14C]glucose appeared in the metabolic products, CO2, lactate, pyruvate, amino acids and glycogen. 3. Fructose at 2.5mm caused a 30% increase in the glucose concentration and a 4-fold increase in the apparent oxidation of [U-14C]-glucose. 4. The formation of 3H2O from [1-3H]-, [2-3H]-, [3-3H]- or [6-3H]-glucose was 2.4, 4.3, 2.15 or 1.6% respectively in the control incubations and 4.1, 10.4, 7.7 or 5.1% with 2.5mm-fructose. 5. Fructose at 7.5 and 25mm decreased the 3H2O yields to less than the control values, but had no apparent effect on the amount of [U-14C]glucose metabolized. 6. In the incubations with 5mm-glucose and 25mm-fructose there were significant decreases in heat production, O2 consumption and in the ratio of O2 uptake to heat output. 7. Fructose at 2.5mm caused a 64% increase in heat output, but only a 43% increase in O2 uptake. 8. The radioisotopic and calorimetric data demonstrate that physiological concentrations of fructose greatly increase metabolism in hepatocytes from starved rats. These data also indicate increased cycling at glucose/glucose 6-phosphate and at fructose 6-phosphate/fructose 1,6-bisphosphate in the presence of 2.5mm-fructose, although the rates of cycling were actually decreased relative to the amount of glucose catabolized. 9. At concentrations of 2.5, 7.5 and 25mm, fructose depressed hepatocyte ATP concentrations by 20, 65 and 80% respectively. Although fructose at 7.5 and 25mm increased glucose and lactate release, O2 consumption, production of heat and formation of3H2O from [1-3H]-, [2-3H]-, [3-3H]- or [6-3H]-glucose were lowered to values equal to, or less than, controls. These effects probably reflect a severe derangement of hepatic metabolism due to excess phosphorylation of fructose when present at high concentrations.

Energy expenditure during stress ulcer formation in vulnerable rats

1989 ◽  
Vol 256 (2) ◽  
pp. R403-R407
Author(s):  
D. Greenberg ◽  
S. H. Ackerman
Keyword(s):  
Food Deprivation ◽  
Heat Production ◽  
Oxidative Metabolism ◽  
Experimental Models ◽  
Gastric Erosion ◽  
Ulcer Formation ◽  
O2 Consumption ◽  
Stress Ulcers ◽  
Rat Pups ◽  
Brown Adipose

Rat pups separated early from their mothers at day 15 become vulnerable to hypothermia and gastric erosion formation when food deprived and physically restrained on postnatal day 30 (S.H. Ackerman, M. A. Hofer, and H. Weiner, Science Wash. DC. 201: 373-376, 1978, and Gastroenterology 75: 649-654, 1978). We tested the hypothesis that this hypothermia is associated with a decrease in oxidative metabolism. We measured O2 consumption of 30-day-old rat pups that had been previously separated at either day 15 (15w) or day 21 (21w). When food was available, 15w rats used as much O2 as 21w rats. When rats were food deprived or food deprived and restrained, 15w rats used significantly less O2 than 21w rats, implying less heat production. We hypothesized that this decrease in heat production during food deprivation and/or restraint was due to impaired thermogenesis resulting from inadequate release of endogenous norepinephrine (NE), which is a stimulant of brown adipose tissue- (BAT) mediated thermogenesis. To test this hypothesis we administered exogenous NE to 15w to 21w rats. Exogenous NE failed to increase O2 consumption in 21w or 15w rats when injected during either food deprivation or restraint. We concluded that 30-day-old 15w rats have decreased oxidative metabolism during food deprivation and restraint and therefore become hypothermic. This decreased oxidative metabolism does not appear to be attributable to insufficient endogenous NE, since it is not reversed by the addition of exogenous NE. We suggest that a decrease in oxidative metabolism may explain susceptibility to stress ulcers in a number of previously reported experimental models.

Oxygen uptake during early cardiogenesis of the chick

1992 ◽  
Vol 262 (4) ◽  
pp. H1224-H1230 ◽  
Author(s):  
E. Raddatz ◽  
M. Servin ◽  
P. Kucera
Keyword(s):  
Oxidative Metabolism ◽  
Cardiac Tissue ◽  
Cardiac Cycle ◽  
Unit Area ◽  
Cardiac Metabolism ◽  
Embryonic Heart ◽  
O2 Consumption ◽  
O2 Uptake ◽  
Metabolic Conditions ◽  
Whole Heart

Oxidative metabolism of the isolated embryonic heart of the chick has been determined using a spectrophotometric technique allowing global as well as localized micromeasurements of the O2 uptake. Entire hearts, excised from embryos of 10 somites (primordia fused, stage 10 HH) and 40 somites (S shaped, stage 20 HH) were placed in a special chamber under controlled metabolic conditions where they continued to beat spontaneously and regularly. During the 32 h of development, the O2 consumption of the whole heart increased from 0.9 +/- 0.1 to 5.3 +/- 0.8 nmol O2/h. These values corrected for protein content were, however, comparable (0.45 nmol O2.h-1.micrograms-1). At stage 10-12, the O2 uptake varied along the cardiac tube (from 0.74 to 1.0 nmol O2.h-1.mm-2). From stage 10 to 20, the O2 uptake per unit area of ventricle wall increased from 0.7 +/- 0.2 to 1.8 +/- 0.2 nmol O2.h-1.mm-2, and the O2 uptake per myocardial volume during one cardiac cycle varied from 7 to 2.5 nmol O2/cm3. These results indicate that, despite an intense morphogenesis, the cardiac tissue has a rather low and stable oxidative metabolism, although the O2 requirement of the whole heart increases significantly. Moreover, the normalized suprabasal aerobic energy expenditure decreases throughout early cardiogenesis. The functional integrity of the isolated embryonic heart combined with the experimental possibilities of the microtechnique make the preparation appropriate for studying the changes in cardiac metabolism during development.

scholarly journals No major thermogenic role for (Na+ + K+)-dependent adenosine triphosphatase apparent in hepatocytes from hyperthyroid rats

1982 ◽  
Vol 202 (3) ◽  
pp. 661-665 ◽  
Author(s):  
D G Clark ◽  
M Brinkman ◽  
O H Filsell ◽  
S J Lewis ◽  
M N Berry
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Atpase Activity ◽  
Heat Production ◽  
Adenosine Triphosphatase ◽  
Heat Output ◽  
Liver Parenchymal ◽  
Dependent Atpase ◽  
Parenchymal Cells ◽  
Isolated Liver

(Na+ + K+)-dependent ATPase activity, heat production and oxygen consumption were increased by 59%, 62% and 75% respectively in hepatocytes from tri-iodothyronine-treated rats. Ouabain at concentrations of 1 and 10 mM decreased oxygen uptake by 2-8% in hepatocytes from euthyroid rats and by 5-15% in hepatocytes from hyperthyroid animals. Heat output was decreased by 4-9% with the glycoside in isolated liver parenchymal cells from the control animals and by 11% in the cells from the tri-iodothyronine-treated animals. These results do not support the hypothesis that hepatic (Na+ + K+)-ATPase plays a major role in increased heat production in hepatocytes from hyperthyroid rats.

The contribution of nitrate respiration to the energy budget of the symbiont-containing clam Lucinoma aequizonata: a calorimetric study

1996 ◽  
Vol 199 (2) ◽  
pp. 427-433
Author(s):  
U Hentschel ◽  
S Hand ◽  
H Felbeck
Keyword(s):  
Heat Production ◽  
Sea Water ◽  
Anaerobic Respiration ◽  
Gill Tissue ◽  
Nitrate Respiration ◽  
Heat Output ◽  
Marine Bivalve ◽  
Calorimetric Study ◽  
Perfusion Medium ◽  
Terminal Electron Acceptor

Heat production and nitrate respiration rates were measured simultaneously in the gill tissue of Lucinoma aequizonata. This marine bivalve contains chemoautotrophic, intracellular, bacterial symbionts in its gill tissue. The symbionts show constitutive anaerobic respiration, using nitrate instead of oxygen as a terminal electron acceptor. An immediate increase in heat production was observed after the addition of nitrate to the perfusion medium of the calorimeter and this was accompanied by the appearance of nitrite in the effluent sea water. The nitrate-stimulated heat output was similar under aerobic and anaerobic conditions, which is consistent with the constitutive nature of nitrate respiration. The amount of heat released was dependent on the concentration of nitrate in the perfusion medium. At nitrate concentrations between 0.5 and 5 mmol l-1, the total heat production was increased over twofold relative to unstimulated baseline values. A mean (±s.e.m.) experimental enthalpy of -130±22.6 kJ mol-1 nitrite (N=13) was measured for this concentration range.

Gastrointestinal blood flow and oxygen consumption in awake newborn piglets: effect of feeding

1983 ◽  
Vol 245 (5) ◽  
pp. G697-G702 ◽  
Author(s):  
P. T. Nowicki ◽  
B. S. Stonestreet ◽  
N. B. Hansen ◽  
A. C. Yao ◽  
W. Oh
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
O2 Consumption ◽  
Gi Tract ◽  
Local Blood Flow ◽  
O2 Uptake ◽  
O2 Extraction ◽  
Gastrointestinal Blood Flow ◽  
O2 Delivery ◽  
Effect Of Feeding

Regional and total gastrointestinal (GI) blood flow, O2 delivery, and whole-gut O2 extraction and O2 consumption were measured before and 30, 60, and 120 min after feeding in nonanesthetized, awake 2-day-old piglets. Cardiac output and blood flow to kidneys, heart, brain, and liver were also determined. Blood flow was measured using the radiolabeled microsphere technique. In the preprandial condition, total GI blood flow was 106 +/- 9 ml X min-1 X 100 g-1, while O2 extraction was 17.2 +/- 0.9% and O2 consumption was 1.99 +/- 0.19 ml O2 X min-1 X 100 g-1. Thirty minutes after slow gavage feeding with 30 ml/kg artificial pig milk, O2 delivery to the GI tract and O2 extraction rose significantly (P less than 0.05) by 35 +/- 2 and 33 +/- 2%, respectively. The increase in O2 delivery was effected by a significant increase in GI blood flow, which was localized to the mucosal-submucosal layer of the small intestine. O2 uptake by the GI tract increased 72 +/- 4% 30 min after feeding. Cardiac output and blood flow to non-GI organs did not change significantly with feeding, whereas arterial hepatic blood flow decreased significantly 60 and 120 min after feeding. The piglet GI tract thus meets the oxidative demands of digestion and absorption by increasing local blood flow and tissue O2 extraction.

Is the function of the renal papilla coupled exclusively to an anaerobic pattern of metabolism?

1979 ◽  
Vol 236 (5) ◽  
pp. F423-F433 ◽  
Author(s):  
J. J. Cohen
Keyword(s):  
Oxidative Metabolism ◽  
Aerobic Glycolysis ◽  
Collecting Duct ◽  
High Rate ◽  
O2 Uptake ◽  
Duct Cells ◽  
Collecting Duct Cells ◽  
Mitochondrial Oxidative Metabolism

It is widely accepted that in vivo the function of the papilla of the mammalian kidney is supported primarily by anaerobic metabolism. As a result, the major source of energy for support of function in the papilla is considered to be derived from glycolysis. This orientation originates from two concepts: 1) that in vivo the gaseous environment of the papilla has such a low PO2 that O2 availability limits O2 consumption, and 2) that papillary tissue has a high rate of glycolysis when compared with either cortical tissue or extrarenal tissues. It has also been tacitly assumed that papillary tissue has a "low" O2 uptake. Review of the measurements of PO2 of papillary tissue and of urine PO2 indicates that the PO2 of papillary tissue should not limit its aerobic mitochondrial oxidative metabolism. While the rate of aerobic glycolysis in papillary tissue is high, simultaneously papillary tissue has a rate of O2 uptake similar to that of liver and higher than that of muscle. The major (two-thirds) source of energy for papillary tissue in vitro is from O2 uptake. That papillary tissue is not exclusively dependent on glucose for its energy requirements is indicated by the greater stimulation of papillary tissue QO2 by succinate than by glucose. Thus, papillary tissue has both a high aerobic mitochondrial oxidative metabolism and a high aerobic glycolytic metabolism. It is suggested that the mechanism for the high rate of aerobic glycolysis in the presence of an adequate O2 supply is due to the relatively small mass of mitochondria in papillary tissue in relation to the amount of work done by the tissue. As a result of the limited rate of ATP production by the mitochondrial electron transport chain, the phosphorylation state ([ATP]/[ADP][Pi]) is reduced and the cytoplasmic redox state ([NAD+]/[NADH]) of the papillary collecting duct cells also becomes more reduced; changes in both ratios enhance the rate of glycolysis. This limited metabolic capacity of the collecting duct cells may permit an excess volume of solute and water to be excreted during volume expansion diuresis. The metabolic characteristics of the papilla, when compared to cortex, also provide a basis for the observed differences in substrate selectivity of cortex and medulla with respect to utilization of glucose and lactate. The experimental approaches that may provide information bearing on the suggested mechanisms for regulation of papillary metabolism in relation to tubular work functions are indicated.

scholarly journals THE EFFECTS OF CAFFEINE ON OXYGEN CONSUMPTION AND CELL DIVISION IN THE FERTILIZED EGG OF THE SEA URCHIN, ARBACIA PUNCTULATA

1945 ◽  
Vol 29 (2) ◽  
pp. 63-72 ◽  
Author(s):  
Ralph Holt Cheney
Keyword(s):  
Cytochrome Oxidase ◽  
Sea Water ◽  
Direct Method ◽  
Relative Effect ◽  
O2 Consumption ◽  
O2 Uptake ◽  
Arbacia Punctulata ◽  
Normal Metabolism ◽  
Main Activity ◽  
Fertilized Egg

1. By means of the Warburg-Barcroft microrespirometer apparatus and the Warburg direct method, the relative effect of caffeine upon the O2 consumption of the fertilized egg of Arbacia punctulata was shown for the following concentrations in sea water: 0.002 per cent (M/10,000), 0.004 per cent (M/5,000), 0.02 per cent (M/1,000), 0.1 per cent (M/200), 0.2 per cent (M/100), 0.5 per cent (M/40), and 2 per cent (M/10). 2. In comparison with the normal eggs (uninhibited, non-caffeine-treated controls), caffeine in concentrations including and greater than 0.1 per cent (M/200) depressed the average uptake from approximately 25 to 61 per cent over the 3 hour period. In a number of instances, as typified by Experiment 10, the effective inhibitory concentration ranged from 0.02 per cent (M/1,000) upward and the degree of depression of the O2 consumption ranged from 10.6 per cent to 60.6 per cent. 3. All caffeine concentrations including and above 0.02 per cent (M/1,000) in the series used, resulted in decreasing the normal rate of cleavage division in the fertilized Arbacia eggs. 4. The higher concentrations (0.5 and 2 per cent) produced a complete blockage of the cleavage process. 5. Complete cleavage inhibition was noted only when the O2 uptake had been depressed to 50 per cent or more of the normal controls. 6. O2 consumption-time relationship data indicate an average depression, in O2 consumption over a 3 hour period, ranging from 25 per cent with a caffeine concentration of 0.1 per cent to a 61 per cent inhibition with a concentration of 2 per cent. 7. Concentrations of less than 0.1 per cent (certainly of less than 0.02 per cent) give variable results and indicate no significant effect. 8. It is inferred from the respiration data presented that it is probable that the inhibition of the O2 consumption in fertilized Arbacia eggs is due to the influence of caffeine upon the main (activity or primary) pathway. It will be observed that there are certain similarities of the caffeine data to the degree of inhibition accomplished by sodium cyanide. Moreover, it has been demonstrated that the cyanide probably acts on the cytochrome oxidase step in the cytochrome oxidase-cytochrome chain of reactions constituting the O2 uptake phase of respiratory metabolism. It is not improbable, therefore, that caffeine also may act upon the cytochrome oxidase enzyme. 9. From the viewpoint of environmental conditions influencing reproductive phenomena, it is of interest that caffeine can affect the normal metabolism of the zygote.

Effects of altered ambient temperature on metabolic rate during CO2 inhalation

1985 ◽  
Vol 58 (5) ◽  
pp. 1592-1596 ◽  
Author(s):  
R. P. Kaminski ◽  
H. V. Forster ◽  
G. E. Bisgard ◽  
L. G. Pan ◽  
S. M. Dorsey ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Heat Production ◽  
Pulmonary Ventilation ◽  
O2 Consumption ◽  
Breathing Frequency ◽  
Ambient Temperatures ◽  
Metabolic Heat ◽  
Respiratory Heat Loss ◽  
Unit Increase ◽  
Stimulation Of

The purpose of this study was to determine if the changes in O2 consumption (VO2) during CO2 inhalation could in part be due to stimulation of thermogenesis for homeothermy. Twelve ponies were exposed for 30-min periods to inspired CO2 (PIco2) levels of less than 0.7, 14, 28, and 42 Torr during the winter at 5 (neutral) and 23 degrees C ambient temperatures (TA) and during the summer at 21 (neutral TA), 30, and 12 degrees C. Elevating TA in both seasons resulted in an increased pulmonary ventilation (VE) and breathing frequency (f) (P less than 0.01) but no significant increase in VO2 (P greater than 0.05). Decreasing TA in the summer resulted in a decrease in VE and f (P less than 0.01) but no significant change in VO2 (P greater than 0.05). At neutral TA in both seasons, VO2 increased progressively (P less than 0.05) as PIco2 was increased from 14 to 28 and 42 Torr. The increases in VO2 during CO2 inhalation were attenuated (P less than 0.05) at elevated TA and accentuated at the relatively cold TA in the summer (P less than 0.05). Respiratory heat loss (RHL) during CO2 inhalation was inversely related to TA. Above a threshold RHL of 2 cal X min-1 X m-2, metabolic heat production (MHP) increased 0.3 cal X min-1 X m-2 for each unit increase in RHL during CO2 inhalation at the neutral and elevated TA. However, during cold stress in the summer, the slope of the MHP-RHL relationship was 1.6, indicating an increased MHP response to RHL.

Oxygen consumption and hemodynamic responses during graded treadmill exercise in the dog

1984 ◽  
Vol 57 (2) ◽  
pp. 601-607 ◽  
Author(s):  
G. A. Ordway ◽  
D. L. Floyd ◽  
J. C. Longhurst ◽  
J. H. Mitchell
Keyword(s):  
Maximal Exercise ◽  
Treadmill Exercise ◽  
Work Load ◽  
Dynamic Exercise ◽  
O2 Consumption ◽  
Treadmill Test ◽  
O2 Uptake ◽  
Hemodynamic Variables ◽  
Linear Relationships ◽  
H 20

A description is given of a technique that provides a relatively simple means by which O2 consumption and hemodynamic variables can be measured in exercising dogs. We used a multistage submaximal treadmill test to study the responses of 10 foxhounds to dynamic exercise. They were also studied during maximal treadmill exercise. O2 consumption increased from 16.3 +/- 1.7 ml O2 X min-1 X kg-1 at rest to 92.9 +/- 9.7 ml O2 X min-1 X kg-1 at a work load of 6.4 km/h, 20% grade and to 111.9 +/- 9.6 ml O2 X min-1 X kg-1 during maximal exercise. Cardiac output (CO) increased from 6.11 +/- 0.45 l/min at rest to 16.91 +/- 1.46 and 17.66 +/- 0.60 l/min at 6.4 km/h, 20% grade and maximal exercise, respectively. Arteriovenous O2 difference increased from 5.8 +/- 0.3 vol% at rest to 12.0 +/- 0.4 and 13.2 +/- 0.7 vol% at 6.4 km/h, 20% grade and maximal exercise, respectively. Heart rate (HR) increased from 116 +/- 7 beats/min at rest to 250 +/- 8 beats/min at 6.4 km/h, 20% grade and to 278 +/- 6 beats/min during maximal exercise. O2 uptake, CO, and arteriovenous O2 difference increased with the onset of exercise, appeared to level at lower work intensities (6.4 km/h, 4 and 8% grade), and increased significantly at each of the higher work intensities (6.4 km/h, 12, 16, and 20% grade). Additionally, we observed linear relationships between O2 consumption and HR (HR = 1.35 X VO2 + 120.5; r = 0.87; P less than 0.001) and between O2 consumption and CO (CO = 5.91 X VO2 + 216.6; r = 0.96; P less than 0.001). Further, the linear relationship between O2 consumption and CO demonstrated in the present study is similar to that observed in humans.

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