scholarly journals Do cardiorespiratory frequencies show entrainment with hopping in the tammar wallaby?

1987 ◽  
Vol 129 (1) ◽  
pp. 251-263 ◽  
Author(s):  
R. V. Baudinette ◽  
B. J. Gannon ◽  
W. B. Runciman ◽  
S. Wells ◽  
J. B. Love
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Arterial Pressure ◽  
Tidal Volume ◽  
Tammar Wallaby ◽  
Metabolic Power ◽  
Macropus Eugenii ◽  
Speed Range ◽  
Lactate Levels ◽  
Blood Lactate Levels

Breathing, heart and gait frequencies, tidal volume, cardiac output, and rates of oxygen consumption were measured in tammar wallabies (Macropus eugenii Desmarest) hopping on a treadmill. At speeds greater than 1.6 ms-1 the rate of metabolic power consumption was independent of hopping speeds. Blood lactate levels within the speed range where VO2 was independent of speed showed a mean increase of 4.8 mmol l-1. During bipedal hopping, the frequencies of breathing and limb movement are phase-locked in the ratio of 1:1. Inspiration begins as the animal leaves the ground and may be a passive process driven by a visceral piston. A relatively large central tendon in the diaphragm may correlate this function. Unlike breathing frequencies, cardiac frequencies show no entrainment with hopping. The site of dissipation of the presumed large arterial pressure excursion is unknown.

Activity before exercise influences recovery metabolism in the lizard Dipsosaurus dorsalis

2000 ◽  
Vol 203 (12) ◽  
pp. 1809-1815
Author(s):  
D.A. Scholnick ◽  
T.T. Gleeson
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Blood Lactate ◽  
Recovery Period ◽  
Maximal Activity ◽  
Warm Up ◽  
Dipsosaurus Dorsalis ◽  
Rate Of Oxygen Consumption ◽  
Lactate Levels ◽  
Blood Lactate Levels

During recovery from even a brief period of exercise, metabolic rate remains elevated above resting levels for extended periods. The intensity and duration of exercise as well as body temperature and hormone levels can influence this excess post-exercise oxygen consumption (EPOC). We examined the influence of activity before exercise (ABE), commonly termed warm-up in endotherms, on EPOC in the desert iguana Dipsosaurus dorsalis. The rate of oxygen consumption and blood lactate levels were measured in 11 female D. dorsalis (mass 41.1 +/− 3.0 g; mean +/− s.e.m.) during rest, after two types of ABE and after 5 min of exhaustive exercise followed by 60 min of recovery. ABE was either single (15 s of maximal activity followed by a 27 min pause) or intermittent (twelve 15 s periods of exercise separated by 2 min pauses). Our results indicate that both single and intermittent ABE reduced recovery metabolic rate. EPOC volumes decreased from 0.261 to 0.156 ml of oxygen consumed during 60 min of recovery when lizards were subjected to intermittent ABE. The average cost of activity (net V(O2) during exercise and 60 min of recovery per distance traveled) was almost 40 % greater in lizards that exercised without any prior activity than in lizards that underwent ABE. Blood lactate levels and removal rates were greatest in animals that underwent ABE. These findings may be of particular importance for terrestrial ectotherms that typically use burst locomotion and have a small aerobic scope and a long recovery period.

Role of Bradycardia and Cold per se in Increasing Mechanical Efficiency of Hypothermic Heart

1958 ◽  
Vol 192 (2) ◽  
pp. 331-334 ◽  
Author(s):  
Henry Badeer ◽  
Avedis Khachadurian
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Arterial Pressure ◽  
Mechanical Efficiency ◽  
Metabolic Effect ◽  
Stroke Work ◽  
Per Se ◽  
Lung Preparation

The relative influence of bradycardia and of cold per se on the oxygen consumption and mechanical efficiency of the dog heart was investigated in the modified heart-lung preparation (11 experiments). Myocardial oxygen uptake was determined under constant arterial pressure and cardiac output in a) normothermia, b) normothermia with bradycardia induced by a cold thermode on the pacemaker, and c) hypothermia producing the same bradycardia as in ( b). At 36.8°C with a rate of 153 beats/min. the efficiency was 8.5% ± 0.3(S.E.), whereas with a rate of 110/min. efficiency was 9.1% ± 0.4(S.E.), a change that is statistically not significant. In hypothermia of 31.5°C with a rate of 110/min. the efficiency was 10.8% ± 0.3(S.E.), an increase that is statistically significant. Performing the same stroke work the hypothermic myocardium consumed less oxygen than the normothermic. It is concluded that the metabolic effect of cold per se is the chief factor responsible for increasing the mechanical efficiency of the hypothermic heart when pressure-volume work is kept constant.

Energetic cost of locomotion in the tammar wallaby

1992 ◽  
Vol 262 (5) ◽  
pp. R771-R778 ◽  
Author(s):  
R. V. Baudinette ◽  
G. K. Snyder ◽  
P. B. Frappell
Keyword(s):  
Oxygen Consumption ◽  
Blood Lactate ◽  
Body Mass ◽  
Energy Cost ◽  
Physiological Adaptation ◽  
Energetic Cost ◽  
Cost Of Locomotion ◽  
Lactate Levels ◽  
Energy Cost Of Locomotion ◽  
Blood Lactate Levels

Rates of oxygen consumption and blood lactate levels were measured in tammar wallabies (Macropus eugenii) trained to hop on a treadmill. In addition, the work required to overcome wind resistance during forward locomotion was measured in a wind tunnel. Up to approximately 2.0 m/s, rates of oxygen consumption increased linearly with speed and were not significantly different from rates of oxygen consumption for a quadruped of similar body mass. Between 2.0 and 9.4 m/s, rates of oxygen consumption were independent of hopping speed, and between 3.9 and 7.9 m/s, the range over which samples were obtained, blood lactate levels were low (0.83 +/- 0.13 mmol.min-1.kg-1) and did not increase with hopping speed. The work necessary to overcome drag increased exponentially with speed but increased the energy cost of locomotion by only 10% at the average speed attained by our fast hoppers. Thus, during hopping, the energy cost of locomotion is effectively independent of speed. At rates of travel observed in the field, the estimated energy cost of transport in large macropods is less than one-third the cost for a quadruped of equivalent body mass. The energetic savings associated with this unique form of locomotion may have been an important physiological adaptation, enabling large macropods to efficiently cover the distances necessary to forage in the semiarid landscapes of Australia.

Altered hemodynamic responses to acute hypoxemia in spontaneously hypertensive rats

1978 ◽  
Vol 234 (3) ◽  
pp. H275-H279 ◽  
Author(s):  
G. M. Walsh ◽  
M. Tsuchiya ◽  
A. C. Cox ◽  
A. J. Tobia ◽  
E. D. Frohlich
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Arterial Pressure ◽  
Spontaneously Hypertensive Rats ◽  
Early Stage ◽  
Peripheral Resistance ◽  
Oxygen Availability ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Total Body Oxygen

Conscious spontaneously hypertensive rats (SHR), 5--7 wk old, were studied hemodynamically by the direct Fick procedure to determine whether high total peripheral resistance (TPR) coexisted with increased oxygen consumption (QO2) at an early stage of hypertension development. Since under resting conditions cardiac output in SHR was not significantly different from normotensive controls, the elevated arterial pressure and QO2 were associated with increased TPR. Arterial hypoxemia was induced to reduce oxygen availability and to assess whether increased TPR in SHR could be reversed by this procedure. During hypoxemia, normotensive controls (WKY) responded with increased cardiac output and decreased arterial pressure and TPR. In contrast, arterial pressure and cardiac output fell in SHR; and the increased TPR persisted. QO2 fell in hypoxemic SHR demonstrating that the relationship between total body oxygen consumption and cardiac output was abnormal in young SHR, and that increased TPR in SHR was not dependent on resting levels of QO2 or oxygen availability. Although QO2 was elevated in SHR compared to age-matched WKY, this condition was not essential for maintained elevated vascular resistance.

Cardiovascular and metabolic responses during burn shock in the guinea pig

1976 ◽  
Vol 231 (3) ◽  
pp. 892-897 ◽  
Author(s):  
RR Wolfe ◽  
HI Miller
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Guinea Pig ◽  
Core Temperature ◽  
Plasma Glucose ◽  
Guinea Pigs ◽  
Tissue Perfusion ◽  
Metabolic Responses ◽  
Burn Shock ◽  
Lactate Levels

The hemodynamic and metabolic responses of fatally burned, nonfatally burned, and unburned control guinea pigs were compared. The burns were induced in temporarily anesthetized animals by immersion to either the xyphoid process (70% fatal) or the midabdomen (100%survival) in boiling water for 3 s. Although cardiac output was reduced in all animals postburn, the survivors (MAG) has higher cardiac outputs at lower arterial pressures than the nonsurvivors (XPN). The postburn lactate levels in the XPN were higher than in the MAG, and the postburn values for pH, oxygen consumption, and core temperature were lower in the XPN. In each group, hyperglycemia was evident for 8 h postburn and terminal plasma glucose concentrations were usually elevated or similar to the prevalue. It was concluded that fatal and nonfatal burn shock were distinguished primarily by differences in tissue perfusion.

Mechanism of Action of Norepinephrine in Hemorrhagic Shock

1958 ◽  
Vol 193 (2) ◽  
pp. 289-293 ◽  
Author(s):  
A. M. Lansing ◽  
J. A. F. Stevenson
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Survival Rate ◽  
Arterial Pressure ◽  
Beneficial Effect ◽  
Hemorrhagic Shock ◽  
Plasma Volume ◽  
Direct Action ◽  
Peripheral Resistance ◽  
Norepinephrine Infusion

Twenty-nine dogs were subjected to a standardized hemorrhagic shock procedure, and various indices were measured in the succeeding 24 hours. During this period, 15 animals received intravenous l-norepinephrine, 0.2– 1.0 µg/kg/min. beginning immediately after the shock procedure. The survival rate of the control animals was 2/14, and of the treated 6/15. Norepinephrine infusion sustained the arterial pressure of the treated animals, not by increasing the peripheral resistance, but rather by maintaining the cardiac output. Since the decline in effective circulating plasma volume that occurred in the first 8 hours after the shock procedure was not prevented by norepinephrine, it is concluded that, in these doses, norepinephrine may exert its beneficial effect by a direct action on the heart. The increased oxygen consumption after the shock procedure in the norepinephrine-treated animals may have been due to a direct effect of the drug on metabolism.

Effect of carbon dioxide on systemic oxygenation, oxygen consumption, and blood lactate levels after bidirectional superior cavopulmonary anastomosis*

2005 ◽  
Vol 33 (5) ◽  
pp. 984-989 ◽  
Author(s):  
Jia Li ◽  
Aparna Hoskote ◽  
Chantal Hickey ◽  
Derek Stephens ◽  
Desmond Bohn ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Blood Lactate ◽  
Cavopulmonary Anastomosis ◽  
Lactate Levels ◽  
Blood Lactate Levels
Sign in / Sign up

Export Citation Format

Share Document