Starvation-induced changes in metabolic rate, blood flow, and regional energy expenditure in rats

Starvation results in an energy-conserving reduction in metabolic rate that has features of an adaptive response. Tissue and organ sites of this response were investigated by examining the effects of starvation for 5 d on tissue blood flow (microsphere method) and regional arteriovenous O2 differences [Formula: see text] in conscious rats resting quietly at 28 °C. Comparison was with fed and overnight-fasted animals. Whole body resting metabolic rates (MR), colonic temperatures (Tc), and tissue weights were also determined. Quantitative changes in energy expenditure (as O2 consumption) were obtained for two regions: the portal-drained viscera (PDV) and the hindquarters (HQ). Fasting overnight resulted in increased blood flow to white adipose tissue (WAT) and decreased flow to the brain, PDV, testes, and skin; however, MR, Tc, the two regional [Formula: see text], and the weights of most tissues were not significantly altered. In comparison with overnight fasting, starvation for 5 d resulted in a 13% reduction in body weight, weight loss in many tissues and organs, a 26% reduction in MR, a decline of 0.5 °C in Tc, decreased [Formula: see text] across both the PDV and HQ, reduced cardiac output, and decreased blood flow to the heart, PDV, skin, WAT, leg muscle, HQ, and the musculoskeletal body as a whole. Utilization of O2 by the PDV and HQ [Formula: see text] declined by amounts that accounted for 22 and 18%, respectively, of the reduction in MR. The reductions in cardiac output (18%) and heart blood flow (36%) indicate that the heart also made a contribution to energy conservation (roughly estimated as 5%). Overall, the data suggest that gut and muscle together accounted for two-thirds to three-quarters of the starvation-induced energy conservation.

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Changes in energy expenditure during the menstrual cycle

British Journal Of Nutrition ◽

10.1079/bjn19890108 ◽

1989 ◽

Vol 61 (2) ◽

pp. 187-199 ◽

Cited By ~ 84

Author(s):

J. T. Bisdee ◽

W. P. T. James ◽

M. A. Shaw

Keyword(s):

Menstrual Cycle ◽

Energy Expenditure ◽

Metabolic Rate ◽

Whole Body ◽

Basal Body Temperature ◽

Late Luteal Phase ◽

Excretion Rates ◽

The Individual ◽

Late Follicular Phase ◽

Exercise Efficiency

1. Eight women were studied under metabolic-ward conditions while consuming a constant diet throughout a single menstrual cycle. Basal body temperature, salivary and urinary hormone concentrations were used in monitoring the cycle and designing the study so that whole-body calorimetry for 36 h was conducted at four phases of the cycle in relation to the time of ovulation.2. The metabolic rate during sleep showed cyclical changes, being lowest in the late follicular phase and highest in the late luteal phase. The increase amounted to 6.1 (SD 2.7)%. Energy expenditure (24 h) also increased but the change was not statistically significant (P> 0.05). Exercise efficiency did not change during the cycle.3. There were no significant changes in plasma thyroxine, 3, 5, 3'-triiodothyronine or free 3, 5, 3'-triiodothyronine concentrations to explain the metabolic rate changes; nor did they relate to urinary luteinizing hormone, pregnanediol-3α-glucuronide or oestrone-3-glucuronide excretion rates. No link with salivary cortisol or progesterone concentrations was observed, but there was a small inverse relation between the individual increase in sleeping metabolic rate and the subjects' falling ratio of urinary oestrone-3-glucuronide: pregnanediol-3α-glucuronide.

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Whole body and hindlimb cardiovascular responses of the anesthetized dog during CO hypoxia

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y84-126 ◽

1984 ◽

Vol 62 (7) ◽

pp. 769-774 ◽

Cited By ~ 7

Author(s):

C. E. King ◽

S. M. Cain ◽

C. K. Chapler

Keyword(s):

Carbon Monoxide ◽

Blood Flow ◽

Cardiac Output ◽

Sympathetic Innervation ◽

Cardiovascular Responses ◽

The Body ◽

Whole Body ◽

Total Resistance ◽

Intact Group ◽

Anesthetized Dogs

To compare with earlier studies of anemic hypoxia obtained by hemodilution, O2 carring capacity was decreased by carbon monoxide (CO) hypoxia. Arterial O2 content was reduced either 50% (moderate CO) or 65% (severe CO). In two groups of anesthetized dogs (moderate and severe CO) hindlimb innervation remained intact while in a third group (moderate CO) the hindlimb was denervated. Measurements were obtained prior to and at 30 and 60 min of CO hypoxia. Cardiac output was elevated at 30 min of CO hypoxia in all groups (p < 0.01) and in the severe CO group at 60 min (p < 0.01). Hindlimb blood flow remained unchanged during CO hypoxia in the intact groups. In the denervated group, hindlimb blood flow was greater (p < 0.05) than that in the intact groups throughout the experiment. A decrease in mean arterial pressure (p < 0.01) in all groups was associated with a fall in total resistance (p < 0.01). Hindlimb resistance remained unchanged during moderate CO hypoxia in the intact group but increased (p < 0.05) in the denervated group. In the severe CO group hindlimb resistance was decreased (p < 0.05) at 60 min. The results indicate that the increase in cardiac output during CO hypoxia was directed to nonmuscle areas of the body and that intact sympathetic innervation was required to achieve this redistribution.

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Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.0968 ◽

2011 ◽

Vol 279 (1728) ◽

pp. 451-456 ◽

Cited By ~ 30

Author(s):

Roger S. Seymour ◽

Sarah L. Smith ◽

Craig R. White ◽

Donald M. Henderson ◽

Daniela Schwarz-Wings

Keyword(s):

Blood Flow ◽

Body Size ◽

Metabolic Rate ◽

Bone Cells ◽

Bone Remodelling ◽

Resting Metabolic Rate ◽

Blood Flow Rate ◽

Whole Body ◽

Long Bone ◽

Cross Sectional

The cross-sectional area of a nutrient foramen of a long bone is related to blood flow requirements of the internal bone cells that are essential for dynamic bone remodelling. Foramen area increases with body size in parallel among living mammals and non-varanid reptiles, but is significantly larger in mammals. An index of blood flow rate through the foramina is about 10 times higher in mammals than in reptiles, and even higher if differences in blood pressure are considered. The scaling of foramen size correlates well with maximum whole-body metabolic rate during exercise in mammals and reptiles, but less well with resting metabolic rate. This relates to the role of blood flow associated with bone remodelling during and following activity. Mammals and varanid lizards have much higher aerobic metabolic rates and exercise-induced bone remodelling than non-varanid reptiles. Foramen areas of 10 species of dinosaur from five taxonomic groups are generally larger than from mammals, indicating a routinely highly active and aerobic lifestyle. The simple measurement holds possibilities offers the possibility of assessing other groups of extinct and living vertebrates in relation to body size, behaviour and habitat.

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Twenty-four-hour energy expenditure and basal metabolic rate measured in a whole-body indirect calorimeter in Gambian men

American Journal of Clinical Nutrition ◽

10.1093/ajcn/51.4.563 ◽

1990 ◽

Vol 51 (4) ◽

pp. 563-570 ◽

Cited By ~ 25

Author(s):

G Minghelli ◽

Y Schutz ◽

A Charbonnier ◽

R Whitehead ◽

E Jéquier

Keyword(s):

Energy Expenditure ◽

Metabolic Rate ◽

Basal Metabolic Rate ◽

Whole Body

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Regional blood flow distribution during the Cushing response: alterations with adrenergic blockade

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1985.248.1.h98 ◽

1985 ◽

Vol 248 (1) ◽

pp. H98-H108

Author(s):

D. G. van Wylen ◽

L. G. D'Alecy

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Regional Blood Flow ◽

Flow Distribution ◽

Peripheral Tissue ◽

Systemic Hypertension ◽

Tissue Blood Flow ◽

Blood Flow Distribution ◽

Beta Receptor ◽

Cushing Response

Regional blood flow distribution (microspheres) and cardiac output (CO, thermal dilution) were measured during the Cushing response in unblocked (UB), beta-receptor-blocked (BB, 2 mg/kg propranolol iv), or alpha-receptor blocked (AB, 0.5 mg/kg + 0.5 mg X kg-1 X min-1 phentolamine iv) chloralose-anesthetized dogs. Intracranial pressure was increased to 150 mmHg by infusion of temperature-controlled artificial cerebrospinal fluid into the cisterna magna. Similar increases in mean arterial pressure were seen in UB and BB, but in AB a Cushing response could not be sustained. In UB, cerebral blood flow (CBF) decreased 50%, coronary blood flow (CoBF) increased 120%, and peripheral tissue blood flow was reduced only in the kidneys (18%) and the intestines (small 22%, large 35%). Blood flow to the other viscera, skin, and skeletal muscle was unchanged. CO (16%) and heart rate (HR, 38%) decreased, and total peripheral resistance (TPR, 68%) and stroke volume (SV, 38%) increased. In BB, CBF decreased 50%, CoBF decreased 20%, and blood flow was reduced 40-80% in all peripheral tissues. CO (69%) and HR (62%) decreased, TPR increased 366%, and SV was unchanged. We conclude that the Cushing response in UB animals combines an alpha-receptor-mediated vasoconstriction with a beta-receptor cardiac stimulation. The beta-mechanism is neither necessary nor sufficient for the hypertension. However, the combination of alpha- and beta-adrenergic mechanisms maintains cardiac output and peripheral tissue blood flow relatively constant while producing a systemic hypertension.

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The physiologic reserve in oxygen carrying capacity: studies in experimental hemodilution

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y86-002 ◽

1986 ◽

Vol 64 (1) ◽

pp. 7-12 ◽

Cited By ~ 107

Author(s):

C. K. Chapler ◽

S. M. Cain

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Oxygen Supply ◽

The Body ◽

Extraction Ratio ◽

Oxygen Extraction ◽

Whole Body ◽

Oxygen Extraction Ratio ◽

Acute Anemia ◽

Total Body Oxygen

The mechanisms by which the body attempts to avoid tissue hypoxia when total body oxygen delivery is compromised during acute anemia are reviewed. When the hematocrit is reduced by isovolemic hemodilution the compensatory adjustments include an increase in cardiac output, redistribution of blood flow to some tissues, and an increase in the whole body oxygen extraction ratio. These responses permit whole body oxygen uptake to be maintained until the hematocrit has been lowered to about 10%. Several factors are discussed which contribute to the increase in cardiac output during acute anemia including the reduction in blood viscosity, sympathetic innervation of the heart, and increased venomotor tone. The latter has been shown to be dependent on intact aortic chemoreceptors. With respect to peripheral vascular responses, the rise in coronary and cerebral blood flows which occur following hemodilution is proportionally greater than the increase in cardiac output while the opposite is true for kidney, liver, spleen, and intestine. Skeletal muscle does not contribute to a redistribution of blood flow to more vital areas during acute anemia despite its relatively large anaerobic capacity. Overall, peripheral compensatory adjustments result in an increased oxygen extraction ratio during acute anemia which reflects a better matching of the limited oxygen supply to tissue oxygen demands. However, some areas such as muscle are relatively overperfused which limits an even more efficient utilization of the reduced oxygen supply. Studies of the response of the microcirculation and the extent to which sympathetic vascular controls are involved in peripheral blood flow regulation are necessary to further appreciate the complex pattern of physiological responses which help ensure survival of the organism during acute anemia.

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Fat feeding causes widespread in vivo insulin resistance, decreased energy expenditure, and obesity in rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1986.251.5.e576 ◽

1986 ◽

Vol 251 (5) ◽

pp. E576-E583 ◽

Cited By ~ 79

Author(s):

L. H. Storlien ◽

D. E. James ◽

K. M. Burleigh ◽

D. J. Chisholm ◽

E. W. Kraegen

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

Energy Expenditure ◽

Metabolic Rate ◽

Brown Adipose Tissue ◽

Whole Body ◽

Brown Adipose ◽

Glucose Output ◽

Fat Feeding

High levels of dietary fat may contribute to both insulin resistance and obesity in humans but evidence is limited. The euglycemic clamp technique combined with tracer administration was used to study insulin action in vivo in liver and individual peripheral tissues after fat feeding. Basal and nutrient-stimulated metabolic rate was assessed by open-circuit respirometry. Adult male rats were pair-fed isocaloric diets high in either carbohydrate (69% of calories; HiCHO) or fat (59% of calories; HiFAT) for 24 +/- 1 days. Feeding of the HiFAT diet resulted in a greater than 50% reduction in net whole-body glucose utilization at midphysiological insulin levels (90-100 mU/l) due to both reduced glucose disposal and, to a lesser extent, failure to suppress liver glucose output. Major suppressive effects of the HiFAT diet on glucose uptake were found in oxidative skeletal muscles (29-61%) and in brown adipose tissue (BAT; 78-90%), the latter accounting for over 20% of the whole-body effect. There was no difference in basal metabolic rate but thermogenesis in response to glucose ingestion was higher in the HiCHO group. In contrast to their reduced BAT weight, the HiFAT group accumulated more white adipose tissue, consistent with reduced energy expenditure. HiFAT feeding also resulted in major decreases in basal and insulin-stimulated conversion of glucose to lipid in liver (26-60%) and brown adipose tissue (88-90%) with relatively less effect in white adipose (0-43%). We conclude that high-fat feeding results in insulin resistance due mainly to effects in oxidative skeletal muscle and BAT.(ABSTRACT TRUNCATED AT 250 WORDS)

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Muscle and whole body metabolism after norepinephrine

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1994.266.6.e877 ◽

1994 ◽

Vol 266 (6) ◽

pp. E877-E884 ◽

Cited By ~ 6

Author(s):

A. V. Kurpad ◽

K. Khan ◽

A. G. Calder ◽

M. Elia

Keyword(s):

Blood Flow ◽

Oxygen Consumption ◽

Fatty Acid ◽

Energy Expenditure ◽

Indirect Calorimetry ◽

Whole Body ◽

Marginal Effect ◽

Nonesterified Fatty Acids ◽

Acid Cycle ◽

Triglyceride Fatty Acid

The effect of an infusion of norepinephrine (0.42 nmol.kg-1.min-1) on energy metabolism in the whole body (using indirect calorimetry and the arteriovenous forearm catheterization techniques in eight healthy young male adults. The activity of the triglyceride-fatty acid cycle, which mainly operates in nonmuscular tissues, was also assessed by measuring glycerol turnover using [2H5]glycerol (to indicate lipolysis) and indirect calorimetry (to indicate net fat oxidation). Norepinephrine increased whole body oxygen consumption by almost 10% (P < 0.01), but the estimated oxygen consumption of muscles tended to decrease. Muscle blood flow (measured by 133Xe) and forearm blood flow (measured by strain-gauge plethysmography) were not significantly affected by norepinephrine, but the rate of uptake of nonesterified fatty acids and beta-hydroxybutyrate increased severalfold (P < 0.05), whereas that of glucose did not. The activity of the triglyceride-fatty acid cycle increased fourfold after norepinephrine administration, having a marginal effect on resting energy expenditure (approximately 1.5%) but accounting for approximately 15% of the increase in whole body energy expenditure. This study provides no evidence that skeletal muscle is an important site for norepinephrine-induced thermogenesis and suggests that an increase in the activity of the triglyceride-fatty acid cycle contributes to the norepinephrine-induced increase in energy expenditure of nonmuscular tissues.

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