A respiratory venous chemoreceptor in the young puppy

1975 ◽  
Vol 38 (5) ◽  
pp. 819-826 ◽  
Author(s):  
K. R. Kollmeyer ◽  
L. I. Kleinman
Keyword(s):  
Minute Ventilation ◽  
Venous Blood ◽  
Blood Gases ◽  
High Ratio ◽  
Mixed Venous Blood ◽  
Extracorporeal Circuit ◽  
Shunt System ◽  
Newborn Animal ◽  
Venous Circulation ◽  
Arterial Blood

An extracorporeal venovenous shunt system utilizing a membrane oxygenator to alter venous blood gases was used to study the regulation of ventilation in 28 newborn and 4 adult dogs. There was no effect of the extracorporeal circuit per se (without the oxygenator in the system) on essential cardiovascular or respiratory function. When the puppies were placed on the extracorporeal circuit with the oxygenator in the system to effect changes in mixed venous blood gas composition there was a significant increase in venous P02 (Pv02), a decrease in venous Pco2 (Pvco2), a rise in venous pH (PHv), and a marked fall in minute ventilation (VE). There were no significant changes in cardiovascular function or arterial blood gases to account for the depression of ventilation. Acute changes in Pvo2 produced appropriate directional changes of VE under conditions where other arterial and venous blood gases were held constant. At a low Pvco2/Paco2 ratio, ventilation was depressed compared to those conditions with a high ratio. At any Pvc02/Paco2 ratio, ventilation could be depressed by raising the Pvo2. In adult animals ventilation could not be altered by changing venous blood gases. These experiments support the existence of a respiratory chemoreceptor sensitive to both PO2 and PCO2 in the prepulmonary or venous circulation of the newborn animal.

Changes in blood gases and acid-base balance in the exercising dog

1962 ◽  
Vol 17 (4) ◽  
pp. 656-660 ◽  
Author(s):  
Ronald L. Wathen ◽  
Howard H. Rostorfer ◽  
Sid Robinson ◽  
Jerry L. Newton ◽  
Michael D. Bailie
Keyword(s):  
Venous Blood ◽  
Blood Gases ◽  
Respiratory Alkalosis ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Mixed Venous Blood ◽  
Acid Base Balance ◽  
Hydrogen Ion Concentration ◽  
Arterial Blood ◽  
Mixed Venous

Effects of varying rates of treadmill work on blood gases and hydrogen ion concentrations of four healthy young dogs were determined by analyses of blood for O2 and CO2 contents, Po2, Pco2, and pH. Changes in these parameters were also observed during 30-min recovery periods from hard work. Arterial and mixed venous blood samples were obtained simultaneously during work through a polyethylene catheter in the right ventricle and an indwelling needle in an exteriorized carotid artery. Mixed venous O2 content, Po2 and O2 saturation fell with increased work, whereas arterial values showed little or no change. Mixed venous CO2 content, Pco2, and hydrogen ion concentration exhibited little change from resting levels in two dogs but increased significantly in two others during exercise. These values always decreased in the arterial blood during exercise, indicating the presence of respiratory alkalosis. On cessation of exercise, hyperventilation increased the degree of respiratory alkalosis, causing it to be reflected on the venous side of the circulation. Submitted on January 8, 1962

scholarly journals Postpneumonectomy alveolar growth does not normalize hemodynamic and mechanical function

1999 ◽  
Vol 87 (2) ◽  
pp. 491-497 ◽  
Author(s):  
Shin-Ichi Takeda ◽  
Murugappan Ramanathan ◽  
Aaron S. Estrera ◽  
Connie C. W. Hsia
Keyword(s):  
Cardiac Output ◽  
Minute Ventilation ◽  
Lung Resection ◽  
Venous Blood ◽  
Structural Response ◽  
Respiratory Muscles ◽  
Blood Gases ◽  
Mixed Venous Blood ◽  
Power Requirement ◽  
Normal Mean

Immature foxhounds underwent 55% lung resection by right pneumonectomy ( n = 5) or thoracotomy without pneumonectomy (Sham, n = 6) at 2 mo of age. Cardiopulmonary function was measured during treadmill exercise on reaching maturity 1 yr later. In pneumonectomized animals compared with Sham animals, maximal oxygen uptake, ventilatory response, and cardiac output during exercise were normal. Arterial and mixed venous blood gases and arteriovenous oxygen extraction during exercise were also normal. Mean pulmonary arterial pressure and resistance were elevated at a given cardiac output. Dynamic ventilatory power requirement was also significantly elevated at a given minute ventilation. These long-term hemodynamic and mechanical abnormalities are in direct contrast to the normal pulmonary gas exchange during exercise in these same pneumonectomized animals reported elsewhere (S. Takeda, C. C. W. Hsia, E. Wagner, M. Ramanathan, A. S. Estrera, and E. R. Weibel. J. Appl. Physiol. 86: 1301–1310, 1999). Functional compensation was superior in animals pneumonectomized as puppies than as adults. These data indicate a limited structural response of conducting airways and extra-alveolar pulmonary blood vessels to pneumonectomy and suggest the development of other sources of adaptation such as those involving the heart and respiratory muscles.

Respiratory and cardiovascular adjustments during exercise of increasing intensity and during recovery in thoroughbred racehorses

1993 ◽  
Vol 179 (1) ◽  
pp. 159-180 ◽  
Author(s):  
P. J. Butler ◽  
A. J. Woakes ◽  
K. Smale ◽  
C. A. Roberts ◽  
C. J. Hillidge ◽  
...  
Keyword(s):  
Dead Space ◽  
Venous Blood ◽  
Lactate Concentration ◽  
Haemoglobin Concentration ◽  
Blood Gases ◽  
Stride Frequency ◽  
Mixed Venous Blood ◽  
Systematic Effect ◽  
Arterial Blood ◽  
Thoroughbred Racehorses

A new design of flowmeter is described and used in a comprehensive study of the respiratory and cardiovascular adjustments that occur during a standardised exercise test in Thoroughbred horses. The flowmeter system and associated lightweight, fibreglass mask (total mass, 0.7 kg) have a maximum dead space of 500 ml and negligible resistance to airflow. They have no systematic effect on blood gases and, together with a rapidly responding mass spectrometer, enable an accurate computation of gas exchange to be performed together with breath-by-breath determination of other respiratory variables. At the highest level of exercise (12 ms-1 on a 3 degrees incline), the rate of oxygen uptake (VO2) and carbon dioxide production (VCO2) increased to 29.4 times and 36.8 times their resting values, respectively. Respiratory minute volume (VE) increased to 27.0 times its resting value, with respiratory frequency (fR) making the major contribution at the walk and trot. However, with increasing cantering speeds, fR changed little as it was locked in a 1:1 fashion to stride frequency, and tidal volume (VT) then made the major contribution to the increase in VE. The ratio of ventilatory dead space (VD) to VT in resting horses was lower than that previously reported in the literature and this could be the result of the different respiratory recording systems that were used. There was a close relationship between VT and stride length at increasing cantering speeds. Despite the fact that alveolar ventilation (VA) was well matched to VO2, there was a significant reduction in arterial PO2 (PaO2) when the horses cantered at 8 ms-1 and this eventually fell to 34% below the resting value. The present data tend to support the idea that VA/Vb (where Vb is cardiac output) inequalities are important in causing this hypoxaemia. However, the reduction in PaO2 was more than compensated for by an increase in haemoglobin concentration, [Hb], so the concentration of oxygen in the arterial blood (CaO2) was significantly above the resting value at all levels of exercise. Both lactate concentration and PaCO2 increased during exercise, causing substantial reductions in pH of both arterial and mixed venous blood. This would have inevitably shifted the oxygen equilibrium curve of the Hb to the right, desaturating the arterial blood and thus exacerbating the effect of the hypoxaemia, as would the almost 4 degrees C rise in blood temperature. The tight respiratory/locomotor linkage might prevent the acidosis and hyperthermia having the stimulatory effects on VE that they have in humans at high work loads.(ABSTRACT TRUNCATED AT 400 WORDS)

Ventilatory and metabolic adaptations to walking and cycling in patients with COPD

2000 ◽  
Vol 88 (5) ◽  
pp. 1715-1720 ◽  
Author(s):  
Paolo Palange ◽  
Silvia Forte ◽  
Paolo Onorati ◽  
Felice Manfredi ◽  
Pietro Serra ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Venous Blood ◽  
Blood Gases ◽  
Peak Exercise ◽  
Chronic Obstructive ◽  
Arterial Blood Gases ◽  
Physiological Dead Space ◽  
Arterial Blood ◽  
Ergometer Exercise ◽  
Walking Capacity

To test the hypothesis that in chronic obstructive pulmonary disease (COPD) patients the ventilatory and metabolic requirements during cycling and walking exercise are different, paralleling the level of breathlessness, we studied nine patients with moderate to severe, stable COPD. Each subject underwent two exercise protocols: a 1-min incremental cycle ergometer exercise (C) and a “shuttle” walking test (W). Oxygen uptake (V˙o 2), CO2output (V˙co 2), minute ventilation (V˙e), and heart rate (HR) were measured with a portable telemetric system. Venous blood lactates were monitored. Measurements of arterial blood gases and pH were obtained in seven patients. Physiological dead space-tidal volume ratio (Vd/Vt) was computed. At peak exercise, W vs. CV˙o 2,V˙e, and HR values were similar, whereasV˙co 2 (848 ± 69 vs. 1,225 ± 45 ml/min; P < 0.001) and lactate (1.5 ± 0.2 vs. 4.1 ± 0.2 meq/l; P < 0.001) were lower, ΔV˙e/ΔV˙co 2(35.7 ± 1.7 vs. 25.9 ± 1.3; P < 0.001) and ΔHR/ΔV˙o 2values (51 ± 3 vs. 40 ± 4; P < 0.05) were significantly higher. Analyses of arterial blood gases at peak exercise revealed higher Vd/Vt and lower arterial partial pressure of oxygen values for W compared with C. In COPD, reduced walking capacity is associated with an excessively high ventilatory demand. Decreased pulmonary gas exchange efficiency and arterial hypoxemia are likely to be responsible for the observed findings.

scholarly journals Respiratory and cardiovascular responses of the exercising chicken to spinal cord cooling at different ambient temperatures. I. Cardiovascular responses and blood gases

1985 ◽  
Vol 114 (1) ◽  
pp. 415-426
Author(s):  
G. M. Barnas ◽  
M. Gleeson ◽  
W. Rautenberg
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Treadmill Exercise ◽  
Venous Blood ◽  
Blood Gases ◽  
Cardiovascular Responses ◽  
Mixed Venous Blood ◽  
Ambient Temperatures ◽  
Arterial Blood ◽  
Exercise Period

We measured oxygen consumption (VO2), heart rate (HR), stroke volume (SV), cardiac output (CO) and mean arterial blood pressure (MBPa) of chickens during 15 min treadmill exercise at 0.5 ms-1 and 0.8 ms-1 at thermoneutral (23 degrees C), low (9 degrees C) and high (34 degrees C) ambient temperature (Ta); the vertebral canal was cooled to 34 degrees C during the middle 5 min of each exercise period. PO2, PCO2, pH and oxygen content (CO2) of the arterial and mixed venous blood were also measured. VO2 during exercise was not significantly affected by Ta. Spinal cord cooling produced definite increases in VO2, CO and SV during 0.5 ms-1 exercise at 9 degrees C; otherwise, effects of spinal cord cooling were not significant. HR, SV and CO were all linearly related to VO2; these relationships were unaffected by spinal cord cooling or Ta. Blood pressure did not increase during exercise. PaCO2 and P-vCO2 did not increase significantly during exercise. The arterial-venous CO2 difference was increased by exercise only at 34 degrees C. The chickens generally hyperventilated at 34 degrees C Ta compared to the other Ta values. No consistent effect on blood gases or on pH and CO2 of the blood could be attributed to spinal cord cooling.

Carbon Dioxide Equilibration in Canine Lungs during Rebreathing and Acute Alkalosis

1979 ◽  
Vol 57 (5) ◽  
pp. 385-388 ◽  
Author(s):  
R. D. Latimer ◽  
G. Laszlo
Keyword(s):  
Whole Blood ◽  
Base Excess ◽  
Venous Blood ◽  
Main Pulmonary Artery ◽  
Mixed Venous Blood ◽  
Arterial Blood ◽  
Significant Difference ◽  
Venous Pco2 ◽  
Pulmonary Arterial ◽  
Gas Pressures

1. The left lower lobe of the lungs of six anaesthetized dogs were isolated by the introduction of a bronchial cannula at thoracotomy. Catheters were introduced into the main pulmonary artery and a vein draining the isolated lobe. 2. Blood-gas pressures and pH were measured across the isolated lobe and compared with gas pressures in alveolar samples from the lobe. 3. When the isolated lobe was allowed to reach gaseous equilibrium with pulmonary arterial blood for 30 min, there was no significant difference between alveolar and pulmonary venous Pco2. Mean values of whole-blood base excess were similar in pulmonary arterial and pulmonary venous blood. 4. After injection of 20 ml of 8·4% sodium bicarbonate solution into a peripheral vein, Pco2, pH and plasma bicarbonate concentrations rose in the mixed venous blood. There was no change of whole-blood base excess across the lung, indicating that HCO−3, as distinct from dissolved CO2, did not enter lung tissue in measurable amounts. 5. No systematic alveolar—pulmonary venous Pco2 differences were demonstrated in this preparation other than those explicable by maldistribution of lobar blood flow.

Respiratory measurements of cardiac output: from elegant idea to useful test

2004 ◽  
Vol 96 (2) ◽  
pp. 428-437 ◽  
Author(s):  
Gabriel Laszlo
Keyword(s):  
Cardiac Output ◽  
Human Subjects ◽  
Venous Blood ◽  
The Body ◽  
Mixed Venous Blood ◽  
Indirect Determination ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Pulmonary Arterial ◽  
Mixed Venous

The measurement of cardiac output was first proposed by Fick, who published his equation in 1870. Fick's calculation called for the measurement of the contents of oxygen or CO2 in pulmonary arterial and systemic arterial blood. These values could not be determined directly in human subjects until the acceptance of cardiac catheterization as a clinical procedure in 1940. In the meanwhile, several attempts were made to perfect respiratory methods for the indirect determination of blood-gas contents by respiratory techniques that yielded estimates of the mixed venous and pulmonary capillary gas pressures. The immediate uptake of nonresident gases can be used in a similar way to calculate cardiac output, with the added advantage that they are absent from the mixed venous blood. The fact that these procedures are safe and relatively nonintrusive makes them attractive to physiologists, pharmacologists, and sports scientists as well as to clinicians concerned with the physiopathology of the heart and lung. This paper outlines the development of these techniques, with a discussion of some of the ways in which they stimulated research into the transport of gases in the body through the alveolar membrane.

Ventilatory responses of hamsters and rats to hypoxia and hypercapnia

1985 ◽  
Vol 59 (6) ◽  
pp. 1955-1960 ◽  
Author(s):  
B. R. Walker ◽  
E. M. Adams ◽  
N. F. Voelkel
Keyword(s):  
Duty Cycle ◽  
Minute Ventilation ◽  
Natural Habitat ◽  
Blood Gases ◽  
Atmospheric Conditions ◽  
Arterial Blood Gases ◽  
Ventilatory Responses ◽  
Arterial Blood ◽  
Rat Experiments ◽  
Fossorial Species

As a fossorial species the hamster differs in its natural habitat from the rat. Experiments were performed to determine possible differences between the ventilatory responses of awake hamsters and rats to acute exposure to hypoxic and hypercapnic environments. Ventilation was measured with the barometric method while the animals were conscious and unrestrained in a sealed plethysmograph. Tidal volume (VT), respiratory frequency (f), and inspiratory (TI) and expiratory (TE) time measurements were made while the animals breathed normoxic (30% O2), hypercapnic (5% CO2), or hypoxic (10% O2) gases. Arterial blood gases were also measured in both species while exposed to each of these atmospheric conditions. During inhalation of normoxic gas, the VT/100 g was greater and f was lower in the hamster than in the rat. Overall minute ventilation (VE/100 g) in the hamster was less than in the rat, which was reflected in the lower PO2 and higher PCO2 of the hamster arterial blood. When exposed to hypercapnia, the hamster increased VE/100 g solely through VT; however, the VE/100 g increase was significantly less than in the rat. In response to hypoxia, the hamster and rat increased VE/100 g by similar amounts; however, the hamster VE/100 g increase was through f alone, whereas the rat increased both VT/100 g and f. Mean airflow rates (VT/TI) were no different in the hamster or rat in each gas environment; therefore most of the ventilatory responses were the result of changes in TI and TE and respiratory duty cycle (TI/TT).

scholarly journals Maximal Fat Oxidation: Comparison between Treadmill, Elliptical and Rowing Exercises

2021 ◽  
pp. 170-178
Author(s):  
Michelle Filipovic ◽  
Stephanie Munten ◽  
Karl-Heinz Herzig ◽  
Dominique D. Gagnon
Keyword(s):  
Oxygen Consumption ◽  
Venous Blood ◽  
Maximal Oxygen Consumption ◽  
Blood Gases ◽  
Fat Oxidation ◽  
Peak Oxygen Consumption ◽  
Whole Body ◽  
Mixed Venous Blood ◽  
Exercise Modality ◽  
Maximal Fat Oxidation

Fat oxidation during exercise is associated with cardio-metabolic benefits, but the extent of which whole-body exercise modality elicits the greatest fat oxidation remains unclear. We investigated the effects of treadmill, elliptical and rowing exercise on fat oxidation in healthy individuals. Nine healthy males participated in three, peak oxygen consumption tests, on a treadmill, elliptical and rowing ergometer. Indirect calorimetry was used to assess maximal oxygen consumption (V̇O2peak), maximal fat oxidation (MFO) rates, and the exercise intensity MFO occurred (Fatmax). Mixed venous blood was collected to assess lactate and blood gases concentrations. While V̇O2peak was similar between exercise modalities, MFO rates were higher on the treadmill (mean ± SD; 0.61 ± 0.06 g·min-1) compared to both the elliptical (0.41 ± 0.08 g·min-1, p = 0.022) and the rower (0.40 ± 0.08 g·min-1, p = 0.017). Fatmax values were also significantly higher on the treadmill (56.0 ± 6.2 %V̇O2peak) compared to both the elliptical (36.8 ± 5.4 %V̇O2peak, p = 0.049) and rower (31.6 ± 5.0 %V̇O2peak, p = 0.021). Post-exercise blood lactate concentrations were also significantly lower following treadmill exercise (p = 0.021). Exercising on a treadmill maximizes fat oxidation to a greater extent than elliptical and rowing exercises, and remains an important exercise modality to improve fat oxidation, and consequently, cardio-metabolic health.

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