Microbial Contributions to the Evolution of the ‘Steady State’ Carbon Dioxide System

1974 ◽  
pp. 37-44
Author(s):  
Richard Y. Morita
Keyword(s):  
Carbon Dioxide ◽  
Steady State

Respiration in man during metabolic alkalosis

1962 ◽  
Vol 17 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Daniel J. Stone
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Lung Function ◽  
Gas Exchange ◽  
Metabolic Alkalosis ◽  
Time Lag ◽  
Respiratory Compensation ◽  
Arterial Ph ◽  
Oral Sodium ◽  
Ventilation Response

A steady state metabolic alkalosis was induced in two subjects over a period of several days utilizing oral sodium bicarbonate in dosages of 50 g/day. The purpose of inducing steady state metabolic alkalosis was to study the effects of such a state on the respiratory center responses to inspired gas mixtures, containing carbon dioxide, and to contrast these results with the control studies. The experiment was so designed that the arterial pH in both subjects tended to return toward normal in the presence of significant increases in blood bicarbonate. Repeated study of ventilation responses with room air and 4% and 6% carbon dioxide in inspired air revealed a definite and significant decrease in ventilation response to carbon dioxide during the periods of steady state alkalosis as compared to the control periods. Normal responses returned after some time lag. A consistent rise in paCOCO2 occurred with alkalosis, thus demonstrating respiratory compensation. In neither subject was total lung function or gas exchange affected by the alkalosis. The experiment was confirmed on several occasions with reproducible results. Note: (With the Research Assistance of Mary Di Lieto) Submitted on May 22, 1961

Methanation of carbon dioxide on Ni-incorporated MCM-41 catalysts: The influence of catalyst pretreatment and study of steady-state reaction

2007 ◽  
Vol 249 (2) ◽  
pp. 370-379 ◽  
Author(s):  
G DU ◽  
S LIM ◽  
Y YANG ◽  
C WANG ◽  
L PFEFFERLE ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Catalyst Pretreatment ◽  
Mcm 41

Inhibition of carbonic anhydrase: its effect on carbon dioxide elimination by the lungs

1959 ◽  
Vol 14 (1) ◽  
pp. 109-115 ◽  
Author(s):  
John C. Mithoefer
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Carbonic Anhydrase ◽  
Normal Animal ◽  
Carbon Dioxide Elimination ◽  
Carbonic Anhydrase Inhibition ◽  
Experimental Approaches

The effect of carbonic anhydrase inhibition on carbon dioxide elimination by the lungs has been studied in dogs by the following four experimental approaches: 1) the alveolar pathway (PaOO2 and PaCOCO2) was measured during the hyperventilation which follows carbonic anhydrase inhibition and compared to the normal pathway at the same hyperventilation. 2) The alveolar gas tensions were measured following carbonic anhydrase inhibition when the ventilation was held constant. 3) The changes in PaCOCO2 were measured when the ventilation was suddenly, artificially changed to a new level in the presence of carbonic anhydrase inhibition and in normal animals. 4) The CO2 output was measured directly during the hyperventilation which results from carbonic anhydrase inhibition, during the same hyperventilation in the normal animal and following carbonic anhydrase inhibition when the ventilation is held constant. These experiments demonstrate an immediate fall in CO2 output relative to the ventilation when carbonic anhydrase is inhibited, resulting in CO2 retention until a new steady state has been reached. An hypothesis is presented to explain the effect of carbonic anhydrase inhibition on CO2 transport. Submitted on March 28, 1958

Tissue carbon dioxide stores: magnitude of acute change in the dog

1964 ◽  
Vol 206 (4) ◽  
pp. 887-890 ◽  
Author(s):  
S. F. Sullivan ◽  
R. W. Patterson ◽  
E. M. Papper
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Dissociation Constant ◽  
Average Rate ◽  
Carbon Dioxide Tension ◽  
Whole Body ◽  
Limiting Factor ◽  
Acute Change ◽  
Washout Curves ◽  
Mixed Venous

Carbon dioxide washout curves were determined in hyperventilated dogs. Direct measurement of mixed venous carbon dioxide tension allowed calculation of changes in whole-body CO2 stores. The average whole-body CO2 dissociation constant in ten studies was 3.73 ml/kg mm. The limiting factor in reaching a new steady-state value was represented by a slow compartment in the washout curve. The average rate constant for this compartment was 0.062 min–1. The slowest compartment in this analysis has a 98% change in 1 hr, therefore the experimentally determined whole-body dissociation constant should closely approximate actual changes in tissue CO2 stores, excluding bone and fat.

Effect of obesity on ventilatory adjustment to exercise

1963 ◽  
Vol 18 (1) ◽  
pp. 19-24 ◽  
Author(s):  
J. Howland Auchincloss ◽  
John Sipple ◽  
Robert Gilbert
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Treadmill Exercise ◽  
Ventilatory Response ◽  
Carbon Dioxide Production ◽  
Exercise Ventilation ◽  
Expired Gas ◽  
Obese Subjects ◽  
Oxygen Tensions ◽  
Alveolar Oxygen

The ventilatory response to treadmill exercise was studied in normal and obese subjects, with an analysis of both the steady and unsteady states of exercise. Ventilation, oxygen consumption, carbon dioxide production, respiratory quotient, and alveolar and mixed expired gas concentrations were measured directly or computed. During the steady state of exercise obese subjects increased their ventilation sufficiently to maintain normal alveolar carbon dioxide tensions. During the first 2 min of exercise hypoventilation was more pronounced in obese subjects and in certain individuals resulted in mild reductions in alveolar oxygen tensions. Obese individuals exercised less efficiently than nonobese as manifested by excessive energy expenditure in relation to weight. Steady-state exercise PaCoCo2 values were higher in those subjects previously shown to be relatively insensitive to inhalation of 5% CO2 but failed to correlate with the speed of ventilatory responsiveness.

Effects of step changes in pH on isometric tetanic tension of toad sartorius muscle

1983 ◽  
Vol 61 (8) ◽  
pp. 830-835 ◽  
Author(s):  
J. M. Renaud ◽  
E. Don Stevens
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Rapid Change ◽  
Carbon Dioxide Concentration ◽  
Physiological Solution ◽  
Acclimation Temperature ◽  
Sartorius Muscle ◽  
Bathing Solution ◽  
Ph Change ◽  
Tetanic Tension

The effect of a rapid change in pHe (pH of bathing solution) on the isometric tetanic tension developed by sartorius muscles of toads acclimated to 5 and 25 °C was measured at 5 and 25 °C. The pH was altered by changing the carbon dioxide concentration of a bicarbonate buffered physiological solution. Acclimation temperature did not modify the response to a rapid change in pH, but test temperature did. Following a pH decrease from 9.0 to 6.0, tetanic tension decreased at a faster rate at 5 °C than at 25 °C. A new steady state was reached in 15 min at 5 °C but in 40 min at 25 °C. Following a pH increase from 6.0 to 8.5, tetanic tension increased at a faster rate at 25 °C than at 5 °C. A new steady state was reached in 60 min at 5 °C but in 10 min at 25 °C. We conclude that the rate of carbon dioxide diffusion through the sartorius muscle is only one factor that determines how rapidly tetanic tension changes following the step change in pH, and that muscle resists pH change more effectively at higher temperatures.

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