The effect of age on mechanisms of exercise tolerance: Reduced arteriovenous oxygen difference causes lower oxygen consumption in older people

Temperature was diminished in a stepwise fashion in the isolated kidney of the dog perfused from a peripheral artery of the original, normothermic animal. Decreased temperature resulted in an appreciable reduction of renal blood flow at constant arterial blood pressure. Increased blood viscosity and vasoconstriction were both responsible for this reduction of flow. Hypothermia also resulted in a reduction in arteriovenous oxygen difference which was roughly proportional to the centigrade temperature. Furthermore, hypothermia exerted a marked but reversible depression of the rate of oxidative metabolism. This effect was relatively more severe than the changes for the body as a whole at equivalent temperatures reported by other investigators.

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Regulation of the Circulation During Exercise

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1956.184.3.613 ◽

1956 ◽

Vol 184 (3) ◽

pp. 613-623 ◽

Cited By ~ 59

Author(s):

A. C. Barger ◽

V. Richards ◽

J. Metcalfe ◽

B. Günther

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Oxygen Consumption ◽

Steady State ◽

Rest Period ◽

Moderate Exercise ◽

Work Intensity ◽

Short Bout ◽

Graded Exercise ◽

Oxygen Difference

Oxygen consumption and cardiac output (direct Fick) have been measured in normal dogs at rest and during graded exercise on the treadmill up to a work intensity of 5 mph and 10°. Systemic and pulmonary artery pressures have also been recorded. The changes in cardiac output produced ‘at rest’ by excitement were frequently as large as those induced by moderate exercise. A short bout of exercise followed by a rest period was far more efficacious in producing lower and more uniform results during rest and subsequent exercise than a prolonged rest period alone. Under such conditions the ‘steady state’ was reached in 3 minutes or less of exercise. The linear relation between oxygen consumption and cardiac output during exercise in the dog is similar to that observed in man, and in the horse. The possible significance of this similarity is discussed and it is suggested that the data are consistent with the hypothesis that the increase in blood flow during exercise is largely the increase in muscle flow with a constant arteriovenous oxygen difference of approximately 14 vol. %.

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Interactions of dietary fat and 2,5-anhydro-d-mannitol on energy metabolism in isolated rat hepatocytes

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00159.2001 ◽

2002 ◽

Vol 282 (3) ◽

pp. R715-R720 ◽

Cited By ~ 9

Author(s):

Hong Ji ◽

Grazyna Graczyk-Milbrandt ◽

Mary D. Osbakken ◽

Mark I. Friedman

Keyword(s):

Oxygen Consumption ◽

Rat Hepatocytes ◽

Isolated Hepatocytes ◽

Metabolic Effects ◽

Atp Content ◽

Isolated Rat Hepatocytes ◽

Palmitate Oxidation ◽

Low Carbohydrate ◽

Lower Oxygen ◽

Hepatocyte Metabolism

The fructose analog 2,5-anhydro-d-mannitol (2,5-AM) stimulates feeding in rats by reducing ATP content in the liver. These behavioral and metabolic effects occur with rats fed a high-carbohydrate/low-fat (HC/LF) diet, but they are prevented or attenuated when the animals eat high-fat/low-carbohydrate (HF/LC) food. To examine the metabolic bases for this effect of diet, we assessed the actions of 2,5-AM on ATP content, oxygen consumption, and substrate oxidation in isolated hepatocytes from rats fed one of the two diets. Compared with cells from rats fed the HC/LF diet (“HC/LF” cells), cells from rats fed the HF/LC diet (“HF/LC” cells) had similar ATP contents but lower oxygen consumption, decreased fructose, and increased palmitate oxidation. 2,5-AM did not decrease ATP content or oxygen consumption in HF/LC cells as much as it did in HC/LF hepatocytes, and it only affected fructose and palmitate oxidation in HC/LF cells.31P-NMR spectroscopy indicated that differences in phosphate trapping accounted for differences in depletion of ATP by 2,5-AM. These results suggest that intake of the HF/LC diet prevents the eating response and attenuates the decline in liver ATP by shifting hepatocyte metabolism to favor fat over carbohydrate as an energy-yielding substrate.

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Adaptation to oxygen deprivation in cultures of human pluripotent stem cells, endothelial progenitor cells, and umbilical vein endothelial cells

AJP Cell Physiology ◽

10.1152/ajpcell.00484.2009 ◽

2010 ◽

Vol 298 (6) ◽

pp. C1527-C1537 ◽

Cited By ~ 70

Author(s):

Hasan Erbil Abaci ◽

Rachel Truitt ◽

Eli Luong ◽

German Drazer ◽

Sharon Gerecht

Keyword(s):

Stem Cells ◽

Endothelial Cells ◽

Oxygen Consumption ◽

Progenitor Cells ◽

Pluripotent Stem Cells ◽

Cell Types ◽

Cellular Responses ◽

Glut 1 ◽

Lower Oxygen ◽

Oxygen Tensions

Hypoxia plays an important role in vascular development through hypoxia-inducible factor-1α (HIF-1α) accumulation and downstream pathway activation. We sought to explore the in vitro response of cultures of human embryonic stem cells (hESCs), induced pluripotent stem cells (iPSCs), human endothelial progenitor cells (hEPCs), and human umbilical cord vein endothelial cells (HUVECs) to normoxic and hypoxic oxygen tensions. We first measured dissolved oxygen (DO) in the media of adherent cultures in atmospheric (21% O2), physiological (5% O2), and hypoxic oxygen conditions (1% O2). In cultures of both hEPCs and HUVECs, lower oxygen consumption was observed when cultured in 1% O2. At each oxygen tension, feeder-free cultured hESCs and iPSCs were found to consume comparable amounts of oxygen. Transport analysis revealed that the oxygen uptake rate (OUR) of hESCs and iPSCs decreased distinctly as DO availability decreased, whereas the OUR of all cell types was found to be low when cultured in 1% O2, demonstrating cell adaptation to lower oxygen tensions by limiting oxygen consumption. Next, we examined HIF-1α accumulation and the expression of target genes, including VEGF and angiopoietins ( ANGPT; angiogenic response), GLUT-1 (glucose transport), BNIP3, and BNIP3L (autophagy and apoptosis). Accumulations of HIF-1α were detected in all four cell lines cultured in 1% O2. Corresponding upregulation of VEGF, ANGPT2, and GLUT-1 was observed in response to HIF-1α accumulation, whereas upregulation of ANGPT1 was detected only in hESCs and iPSCs. Upregulation of BNIP3 and BNIP3L was detected in all cells after 24-h culture in hypoxic conditions, whereas apoptosis was not detectable using flow cytometry analysis, suggesting that BNIP3 and BNIP3L can lead to cell autophagy rather than apoptosis. These results demonstrate adaptation of all cell types to hypoxia but different cellular responses, suggesting that continuous measurements and control over oxygen environments will enable us to guide cellular responses.

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Effect of Age on the Oxygen Consumption and Glucose Uptake by the Elastic Cartilage of Rat

Gerontology ◽

10.1159/000211601 ◽

1967 ◽

Vol 13 (3) ◽

pp. 173-176 ◽

Cited By ~ 2

Author(s):

B.K. Patnaik

Keyword(s):

Oxygen Consumption ◽

Glucose Uptake ◽

Elastic Cartilage ◽

Effect Of Age

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Prolonged static stretching causes acute, nonmetabolic fatigue and impairs exercise tolerance during severe-intensity cycling

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2019-0981 ◽

2020 ◽

Vol 45 (8) ◽

pp. 902-910

Author(s):

Alessandro L. Colosio ◽

Massimo Teso ◽

Silvia Pogliaghi

Keyword(s):

Oxygen Consumption ◽

Exercise Tolerance ◽

Muscle Activation ◽

Metabolic Response ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Time To Exhaustion ◽

Static Stretching ◽

Perception Of Effort ◽

Severe Intensity

We tested the hypothesis that static stretching, an acute, nonmetabolic fatiguing intervention, reduces exercise tolerance by increasing muscle activation and affecting muscle bioenergetics during cycling in the “severe” intensity domain. Ten active men (age, 24 ± 2 years; body mass, 74 ± 11 kg; height, 176 ± 8 cm) participated in identical constant-load cycling tests of equal intensity, of which 2 tests were carried out under control conditions and 2 were done after stretching. This resulted in a 5% reduction of maximal isokinetic sprinting power output. We measured (i) oxygen consumption, (ii) electromyography, (iii) deoxyhemoglobin, (iv) blood lactate concentration; (v) time to exhaustion, and (vi) perception of effort. Finally, oxygen consumption and deoxyhemoglobin kinetics were determined. Force reduction following stretching was accompanied by augmented muscle excitation at a given workload (p = 0.025) and a significant reduction in time to exhaustion (p = 0.002). The time to peak oxygen consumption was reduced by stretching (p = 0.034), suggesting an influence of the increased muscle excitation on the oxygen consumption kinetics. Moreover, stretching was associated with a mismatch between O2 delivery and utilization during the isokinetic exercise, increased perception of effort, and blood lactate concentration; these observations are all consistent with an increased contribution of the glycolytic energy system to sustain the same absolute intensity. These results suggest a link between exercise intolerance and the decreased ability to produce force. Novelty We provided the first characterization of the effects of prolonged stretching on the metabolic response during severe cycling. Stretching reduced maximal force and augmented muscle activation, which in turn increased the metabolic response to sustain exercise.

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Effect of changes in blood CO2 level on coronary flow and myocardial O2 consumption

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1960.199.2.349 ◽

1960 ◽

Vol 199 (2) ◽

pp. 349-354 ◽

Cited By ~ 39

Author(s):

H. Feinberg ◽

A. Gerola ◽

L. N. Katz

Keyword(s):

Oxygen Consumption ◽

Coronary Flow ◽

Myocardial Oxygen Consumption ◽

Gas Mixture ◽

Aortic Blood ◽

Anesthetized Dogs ◽

Myocardial O2 Consumption ◽

Aortic Blood Pressure ◽

Co2 Level ◽

Oxygen Difference

The effect of hypo- and hypercapnia—induced by changing the respiratory gas mixture—on coronary flow and myocardial oxygen consumption was observed at constant cardiac output and over a broad range of pressure-loads in open-chested, anesthetized dogs. The correlation of cardiac effort (as indexed by the product of heart rate and mean aortic blood pressure) with myocardial oxygen consumption was not altered by increasing or decreasing the arterial CO2 content. Coronary blood flow was observed to be increased relative to the cardiac effort during hypercapnia but not during hypocapnia. The coronary arteriovenous oxygen difference and the percentage of oxygen extracted decreased during hypercapnia pari passu with the increase in venous oxygen content.

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