scholarly journals Ventilation, Oxygen Uptake and Haemolymph Oxygen Transport, Following Enforced Exhausting Activity in the Dungeness Crab Cancer Magister

1979 ◽  
Vol 80 (1) ◽  
pp. 271-285 ◽  
Author(s):  
B. R. McMAHON ◽  
D. G. McDONALD ◽  
C. M. WOOD
Keyword(s):  
Cardiac Output ◽  
Oxygen Uptake ◽  
Oxygen Transport ◽  
Lactate Concentration ◽  
Fold Increase ◽  
Oxygen Extraction ◽  
Oxygen Release ◽  
Cancer Magister ◽  
Metabolic Scope ◽  
Dungeness Crabs

Scaphognathite and heart-pumping frequencies, ventilation volume, cardiac output, oxygen uptake and oxygen transport by haemolymph have been studied in unrestrained Dungeness crabs (Cancer magister) before, immediately after, and during recovery from 20 min of enforced exhausting activity. Exercise increased oxygen uptake 4-fold. This increase was achieved by more than 2-fold elevation of both ventilation volume and cardiac output and by greater participation of haemocyanin in oxygen delivery. The elevated ventilation volume resulted entirely from an increase in scaphognathite pumping frequency, while the rise in cardiac output resulted largely from increase in stroke volume. Prior to exercise haemocyanin accounts for less than 50% of the oxygen delivered to the tissues. Following exercise this increases to over 80%, the additional oxygen release being mediated by a depression of prebranchial oxygen tension and a substantial Bohr effect resulting from build up of lactate ion in the haemolymph and subsequent fall in pH. These changes allowed % oxygen extraction from branchial water to be maintained at 28% despite a 2-fold increase in ventilation volume, and allowed an increase in %. oxygen extraction by the tissues. Despite these changes oxygen supply fell below demand during exercise, and considerable anaerobic metabolism resulted, as evidenced by a 9-fold increase in haemolymph lactate concentration. The resulting oxygen debt required 8–24 h for repayment. Aerobic metabolic scope, and mechanisms of increasing oxygen uptake and transport in this crab are compared with those of a range of fish species.

Circulatory changes in man during mild supine exercise

1961 ◽  
Vol 16 (2) ◽  
pp. 279-282 ◽  
Author(s):  
John T. Reeves ◽  
Robert F. Grover ◽  
Giles F. Filley ◽  
S. Gilbert Blount
Keyword(s):  
Cardiac Output ◽  
Oxygen Uptake ◽  
Oxygen Transport ◽  
Oxygen Extraction ◽  
Tissue Oxygen ◽  
Total Blood ◽  
Normal Men ◽  
Total Blood Flow ◽  
Extraction Mechanisms ◽  
Oxygen Difference

Cardiac output and femoral A-V oxygen difference were measured in each of seven normal men at rest and during several stints of supine exercise to investigate the mechanisms of oxygen transport for stepwise increments of oxygen uptake. The femoral A-V oxygen difference increased sharply for mild exercise and showed smaller further increase for heavier exercise stints. The pulmonary A-V oxygen difference followed a similar behavior where the changes were of smaller magnitude. For mild exercise, increasing oxygen transport apparently depends to a greater extent on increasing femoral tissue oxygen extraction and to a lesser extent on increased femoral and total blood flow. For heavier exertion, increasing oxygen transport depends to a greater extent on increasing flow and to a smaller extent on a widening tissue oxygen extraction. Mechanisms which are utilized to meet the increased metabolic demands of exercise depend in part upon the severity of the exertion. Cardiac output appears not to be a simple linear function of oxygen uptake for various metabolic demands ranging from rest to heavy exercise. Submitted on August 8, 1960

Appearance of excess lactate in anesthetized dogs during anemic and hypoxic hypoxia

1965 ◽  
Vol 209 (3) ◽  
pp. 604-610 ◽  
Author(s):  
Stephen M. Cain
Keyword(s):  
Cardiac Output ◽  
Oxygen Uptake ◽  
Oxygen Transport ◽  
Liver Dysfunction ◽  
Hypoxic Hypoxia ◽  
Blood Gas ◽  
Total Oxygen ◽  
Anesthetized Dogs ◽  
Lactate And Pyruvate ◽  
Mixed Venous

Ten anesthetized, splenectomized dogs were made progressively anemic by replacement of blood with warmed dextran to approximate hematocrits of 30, 20, 15, and 10%. A second group of 10 dogs was made progressively hypoxic by having them inspire 11.4, 9.5, 8.0, and 5.9% O2 in N2. Blood gas contents, pH, and gas tensions were measured in arterial and mixed venous bloods. Cardiac output was calculated from the arteriovenous O2 difference and the O2 uptake. Excess lactate was calculated from measured levels of lactate and pyruvate in blood water. Excess lactate appeared at higher mixed venous Po2 in anemic animals than in hypoxic, 40 mm Hg versus 20 mm Hg. When related to total oxygen transport, however, excess lactate appeared at about the same point (12 ml/kg per min) in both groups. Because liver has been shown to reduce its oxygen uptake with any lowering of perfusate oxygen content, it was suggested that the excess lactate measured during both anemic and hypoxic hypoxia in anesthetized dogs is largely the result of liver dysfunction with respect to lactate.

Effects of extreme pH on the physiology of the Australian 'yabby' Cherax destructor: acute and chronic changes in haemolymph oxygen levels, oxygen consumption and metabolic levels

1995 ◽  
Vol 198 (2) ◽  
pp. 409-418 ◽  
Author(s):  
B Ellis ◽  
S Morris
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Oxygen Transport ◽  
Consumption Rate ◽  
Lactate Concentration ◽  
Acid Water ◽  
Freshwater Crayfish ◽  
Glucose Levels ◽  
Cherax Destructor ◽  
Growth And Reproduction

Respiration and metabolism of the freshwater crayfish Cherax destructor were investigated with respect to the acidification and alkalization of its environment. Crayfish were exposed for up to 504 h (21 days) to pH 4.5, pH 7.1 (control) or pH 8.0 water and oxygen consumption rate, haemolymph oxygen transport and haemolymph glucose and lactate concentrations were determined. The effect of reducing environmental [Ca2+] in acid water from 500 to 50 µmol l-1 was also examined. In acid water (500 µmol l-1 Ca2+), oxygen uptake by Cherax was reduced by 79 % after 504 h (21 days) compared with 'control' animals (pH 7.1, 500 µmol l-1 Ca2+). Haemolymph lactate concentration (mean 0.6 mmol l-1) remained constant, indicating that anaerobiosis was not important, while glucose concentrations were regulated within the range of control values (0.32±0.01 mmol l-1). The arterial-venous CO2 difference of Cherax haemolymph decreased after 288 h and PaO2 increased from 11.1±0.5 mmHg to 42.4±1.0 mmHg between 96 h and 288 h. Decreased oxygen uptake and delivery without compensatory increases in anaerobiosis or glucose levels describe a hypometabolic response to low pH. The hypometabolic response of Cherax was greater in alkaline water as shown by a 53 % reduction in O2 uptake rate compared with a 44 % reduction in acid-exposed (500 µmol l-1 Ca2+) animals after 96 h. This decrease in M(dot)O2 of alkaline-exposed animals was correlated with decreased haemolymph glucose levels (from 0.32±0.01 at 0 h to 0.06±0.01 mmol l-1 at 96 h). Lowering the [Ca2+] of the water both increased the magnitude of the effects of acid exposure and elicited further changes in haemolymph oxygen transport. The maintenance of high haemolymph PO2 during pH stress appears to reduce the involvement of haemocyanin, since this promotes decreased a­v CO2. Hypometabolism probably permits Cherax to conserve resources that might otherwise be used, however, for growth and reproduction. The implications for the fitness of the animal are discussed.

Non-invasive Measurement of Cardiac Output and Ventricular Ejection Fractions in Chronic Cardiac Failure: Relationship to Impaired Exercise Tolerance

1997 ◽  
Vol 93 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Ian C. Steele ◽  
ANN Moore ◽  
Anne-Marie Nugent ◽  
Marshall S. Riley ◽  
Norman P. S. Campbell ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Cardiac Failure ◽  
Exercise Tolerance ◽  
Perceived Exertion ◽  
Lactate Concentration ◽  
Submaximal Exercise ◽  
Chronic Cardiac Failure ◽  
And Control

1. The role of cardiac output limitation in the pathophysiology of exercise in patients with chronic failure remains undefined. During steady-state submaximal exercise, oxygen uptake is similar in patients and control subjects, but it is not known if cardiac output is also similar. We wished to determine if the reduced exercise tolerance of patients with chronic cardiac failure during such exercise is related to reduced cardiac output, or to peripheral factors. 2. Ten male patients with stable chronic failure and ten age-matched male normal controls were studied at rest and during exercise. Each subject performed a familiarization exercise test, a symptom-limited maximal exercise test and two submaximal exercise tests. Cardiac output was measured by a carbon dioxide rebreathing method. We also measured oxygen consumption, ventilation, Borg score of perceived exertion and venous lactate concentration, and ejection fractions. 3. As expected, patients had lower peak oxygen consumption [median (range) 1.18 (0.98–1.76) versus 1.935 (1.53–2.31) 1/min; P < 0.001], lower peak venous lactate concentration but a similar overall level of perceived exertion. At the same submaximal workload, patients and control subjects had similar oxygen consumption [0.67 (0.59–0.80) versus 0.62 (0.52–0.82) 1/min] and cardiac output [6.92 (5.79–9.76) versus 7.3 (5.99–10.38) 1/min] but the patients had a greater perceived level of exertion [Borg score: 4 (1–6) versus 3 (1–5); P < 0.005], higher venous lactate concentration [1.6 (1–3.3) versus 1.14 (0.7–1.7) mmol/l; P < 0.05] and higher heart rate [106 (89–135) versus 87 (69–112) beats/min;P < 0.005]. 4. During submaximal exercise at a similar absolute workload, patients with cardiac failure have a similar oxygen uptake and cardiac output but greater anaerobiosis and increased fatigue when compared with normal subjects. These findings appear to relate predominantly to changes that occur in the periphery rather than abnormalities of central cardiac function.

Circulation, oxygen transport, and activity in the crayfish

1981 ◽  
Vol 240 (1) ◽  
pp. R99-R105 ◽  
Author(s):  
P. S. Rutledge
Keyword(s):  
Cardiac Output ◽  
Oxygen Uptake ◽  
Stroke Volume ◽  
Oxygen Transport ◽  
Uptake Rate ◽  
Oxygen Uptake Rate ◽  
Maximum Activity ◽  
Active Oxygen ◽  
Routine Activity ◽  
Fick Principle

Heart and ventilation frequencies, oxygen uptake rate, hemocyanin concentration, and pre- and postbranchial PO2 and pH were measured in unrestrained crayfish (Pacifastacus leniuculus) immediately following routine and forced (maximum) activity. Experiments were performed at 20 degrees C, the temperature of maximum scope for activity in this species, and at 10 and 25 degrees C. A procedure for using N-ethylmaleimide as an anticoagulant in hemolymph sampling is described. Hemocyanin oxygen saturation, oxygen content of pre- and postbranchial hemolymph, cardiac output, and stroke volume were estimated from the measured parameters. PO2 of postbranchial hemolymph sampled immediately after routine activity was low (9-12 Torr), accompanied by hemocyanin oxygen saturations of 55-75%. Maximum forced activity for 10 min caused further reduction in these values. Thus hemocyanin is apparently not usually saturated with oxygen in these crayfish. Cardiac output, as estimated by the Fick principle, was high (at 20 degrees C, 236 ml x kg-1 x min-1 for routine activity and 969 ml x kg-1 x min-1 for forced activity). Evidence is presented that ventilation, rather than circulation, limits active oxygen uptake and scope for activity both above and below 20 degrees C.

scholarly journals Impaired oxygen uptake kinetics in heart failure with preserved ejection fraction

Heart ◽  
2019 ◽  
Vol 105 (20) ◽  
pp. 1552-1558 ◽  
Author(s):  
Christopher M Hearon Jr ◽  
Satyam Sarma ◽  
Katrin A Dias ◽  
Michinari Hieda ◽  
Benjamin D Levine
Keyword(s):  
Heart Failure ◽  
Cardiac Output ◽  
Ejection Fraction ◽  
Oxygen Uptake ◽  
Submaximal Exercise ◽  
Oxygen Extraction ◽  
Peak Exercise ◽  
Preserved Ejection Fraction ◽  
Metabolic Demand ◽  
Oxygen Utilisation

ObjectiveThe time needed to increase oxygen utilisation to meet metabolic demand (V̇O2 kinetics) is impaired in heart failure (HF) with reduced ejection fraction and is an independent risk factor for HF mortality. It is not known if V̇O2 kinetics are slowed in HF with preserved ejection fraction (HFpEF). We tested the hypothesis that V̇O2 kinetics are slowed during submaximal exercise in HFpEF and that slower V̇O2 kinetics are related to impaired peripheral oxygen extraction.MethodsEighteen HFpEF patients (68±7 years, 10 women) and 18 healthy controls (69±6 years, 10 women) completed submaximal and peak exercise testing. Cardiac output (acetylene rebreathing, Q̇c), ventilatory oxygen uptake (V̇O2, Douglas bags) and arterial-venous O2 difference (a-vO2 difference) derived from Q̇c and V̇O2 were assessed during exercise. Breath-by-breath O2 uptake was measured continuously throughout submaximal exercise, and V̇O2 kinetics was quantified as mean response time (MRT).ResultsHFpEF patients had markedly slowed V̇O2 kinetics during submaximal exercise (MRT: control: 40.1±14.2, HFpEF: 65.4±27.7 s; p<0.002), despite no relative impairment in submaximal cardiac output (Q̇c: control: 8.6±1.7, HFpEF: 9.7±2.2 L/min; p=0.79). When stratified by MRT, HFpEF with an MRT ≥60 s demonstrated elevated Q̇c, and impaired peripheral oxygen extraction that was apparent during submaximal exercise compared with HFpEF with a MRT <60 s (submaximal a-vO2 difference: MRT <60 s: 9.7±2.1, MRT ≥60 s: 7.9±1.1 mL/100 mL; p=0.03).ConclusionHFpEF patients have slowed V̇O2 kinetics that are related to impaired peripheral oxygen utilisation. MRT can identify HFpEF patients with peripheral limitations to submaximal exercise capacity and may be a target for therapeutic intervention.

Postnatal changes in critical cardiac output and oxygen transport in conscious lambs

1987 ◽  
Vol 253 (1) ◽  
pp. H100-H106 ◽  
Author(s):  
J. T. Fahey ◽  
G. Lister
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Oxygen Transport ◽  
Oxygen Extraction ◽  
Base Line ◽  
Arterial Lactate ◽  
Acid Accumulation ◽  
Systemic Oxygen ◽  
The Right ◽  
Lower Cardiac Output

We lowered cardiac output progressively in a controlled, stepwise fashion in conscious, unsedated lambs to determine the critical cardiac output or systemic oxygen delivery (the level at which oxygen consumption decreased abruptly). With the use of incremental inflation of a balloon-tipped catheter placed in the right atrium to lower cardiac output, we examined the response of oxygen consumption, systemic oxygen transport, fractional oxygen extraction, arterial lactate, and blood pressure. We studied lambs at 2 (n = 5), 4 (n = 5), and 8 wk (n = 6) of age and found that the 4-wk-old lambs reached critical values of cardiac output and systemic oxygen transport with the smallest proportional decreases from base-line values. Therefore, the 4-wk-old lambs were the least tolerant of acute decreases in cardiac output. We also found that fractional oxygen extraction was able to increase even after critical systemic oxygen transport was achieved. Furthermore, we found at every age that lactic acid accumulation began when the critical level of cardiac output was reached.

Group B Streptococcus-induced acidosis in newborn swine: regional oxygen transport and lactate flux

1992 ◽  
Vol 72 (1) ◽  
pp. 272-277 ◽  
Author(s):  
E. S. Barefield ◽  
W. Oh ◽  
B. S. Stonestreet
Keyword(s):  
Metabolic Acidosis ◽  
Oxygen Uptake ◽  
Oxygen Delivery ◽  
Group B Streptococcus ◽  
Lactate Concentration ◽  
Oxygen Metabolism ◽  
Oxygen Extraction ◽  
Vascular Bed ◽  
Vascular Beds ◽  
Group B

To investigate the mechanism of metabolic acidosis resulting from group B streptococcal sepsis, oxygen metabolism and lactate flux of the cerebrum, hindlimb, liver, splanchnic organs, and systemic vascular bed as a whole were examined. Nine 3- to 5-day-old awake and spontaneously breathing piglets were studied before and after 3, 4, and 5 h of continuous live group B Streptococcus infusion. After 5 h, oxygen delivery was decreased to all organs and to the whole systemic vascular bed. Increased oxygen extraction compensated for reduced oxygen delivery in the liver and splanchnic organs; however, it only partially offset reduced oxygen delivery to the hindlimb and systemic vascular bed. Cerebral oxygen extraction did not increase. As a result, oxygen uptake was reduced in the cerebrum, hindlimb, and systemic vascular bed. At 5 h of bacterial infusion, arterial lactate concentration was increased with regional lactate efflux from the cerebrum and hindlimb and influx to the liver (P less than 0.05 vs. zero or no net flux). We conclude that group B Streptococcus-induced metabolic acidosis is associated with regional lactate efflux from vascular beds in which oxygen uptake is reduced. We speculate that the quantity of net lactate efflux from vascular beds with insufficient oxygen uptake exceeds the net influx into organs such as the liver, resulting in metabolic acidosis.

scholarly journals Physiological responses and cycle characteristics during double-poling versus diagonal-stride roller-skiing in junior cross-country skiers

2021 ◽  
Author(s):  
Erik P. Andersson ◽  
Irina Hämberg ◽  
Paulo Cesar Do Nascimento Salvador ◽  
Kerry McGawley
Keyword(s):  
Oxygen Uptake ◽  
Perceived Exertion ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Peak Oxygen Uptake ◽  
Submaximal Exercise ◽  
Rating Of Perceived Exertion ◽  
Time To Exhaustion ◽  
Double Poling ◽  
Cross Country

Abstract Purpose This study aimed to compare physiological factors and cycle characteristics during cross-country (XC) roller-skiing at matched inclines and speeds using the double-poling (DP) and diagonal-stride (DS) sub-techniques in junior female and male XC skiers. Methods Twenty-three well-trained junior XC skiers (11 women, 12 men; age 18.2 ± 1.2 yr.) completed two treadmill roller-skiing tests in a randomized order using either DP or DS. The exercise protocols were identical and included a 5 min warm-up, 4 × 5 min submaximal stages, and an incremental test to exhaustion, all performed at a 5° incline. Results No significant three-way interactions were observed between sex, submaximal exercise intensity, and sub-technique. For the pooled sample, higher values were observed for DP versus DS during submaximal exercise for the mean oxygen uptake kinetics response time (33%), energy cost (18%), heart rate (HR) (9%), blood lactate concentration (5.1 versus 2.1 mmol·L−1), rating of perceived exertion (12%), and cycle rate (25%), while cycle length was lower (19%) (all P < 0.001). During the time-to-exhaustion (TTE) test, peak oxygen uptake ($$\dot{V}$$ V ˙ O2peak), peak HR, and peak oxygen pulse were 8%, 2%, and 6% lower, respectively, for DP than DS, with a 29% shorter TTE during DP (pooled data, all P < 0.001). Conclusion In well-trained junior XC skiers, DP was found to exert a greater physiological load than DS during uphill XC roller-skiing at submaximal intensities. During the TTE test, both female and male athletes were able to ski for longer and reached markedly higher $$\dot{V}$$ V ˙ O2peak values when using DS compared to DP.

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