scholarly journals THE RESPIRATORY QUOTIENT OF FROG NERVE DURING STIMULATION

1927 ◽  
Vol 11 (2) ◽  
pp. 175-191 ◽  
Author(s):  
Wallace O. Fenn
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Diffusion Coefficients ◽  
Time Course ◽  
Oxygen Intake ◽  
Dissociation Curve ◽  
Similar Time ◽  
High Co2 ◽  
Carbon Dioxide Output ◽  
Carbon Dioxide Dissociation Curve

1. By means of a differential volumeter the increased oxygen consumption and the increased carbon dioxide output of frog nerve during and after stimulation have been observed. 2. Measurements of the R.Q. of nerve by this method are complicated by the retention of carbon dioxide. Attempts were made to avoid this (a) by studying the nerves at high CO2 tensions to make the retention small and (b) by calculating the amount of CO2 retained from the carbon dioxide dissociation curve of nerve and applying this value as a correction. 3. The results of both those methods when averaged together give an R.Q. of the excess metabolism of 1.19 and an R.Q. of the resting nerve of 0.97. 4. Observations on the time course of the gas exchange during stimulation indicate a delay in the appearance of the extra carbon dioxide output relative to the oxygen intake. 5. Very similar time curves can be calculated from the diffusion coefficients and the solubilities of the oxygen and the carbon dioxide.

scholarly journals The duration of the recovery period following strenuous muscular exercise

1933 ◽  
Vol 113 (783) ◽  
pp. 327-344 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Normal Values ◽  
Recovery Period ◽  
Oxygen Intake ◽  
Respiratory Metabolism ◽  
Carbon Dioxide Output ◽  
Steady Level ◽  
Made In

There are a variety of ways in which the duration of the recovery period after exercise can be determined. The method most frequently employed depends upon observations of the respiratory metabolism. This method has been chosen because the respiratory changes due to exercise can be followed with reasonable ease and accuracy, and because these changes are among the last of the more obvious effects of the exercise to disappear during recovery. In addition, interesting data concerning the effects of exercise on respiratory metabolism can be collected during the determination of the duration of the recovery period when this method is used. In determining the duration of the recovery period by observation of the respiratory metabolism, it is necessary to decide when the carbon dioxide output and oxygen intake have returned to their normal values and are no longer affected by the process of recovery from the exercise. This decision has been made in a variety of ways by different investigators. Some have made one or more pre-exercise determinations of the subject's basal oxygen intake and carbon dioxide output. Recovery was said to be complete when the carbon dioxide output and oxygen consumption returned to these values after exercise. Others found that the oxygen consumption did not return to the pre-exercise level within a reasonable length of time, but remained above normal for several hours. They considered that recovery was complete when the carbon dioxide output and oxygen intake returned to a steady level after exercise, even if the level was not the same as that before exercise.

scholarly journals THE CARBON DIOXIDE DISSOCIATION CURVE OF LIVING MAMMALIAN MUSCLE

1932 ◽  
Vol 95 (1) ◽  
pp. 95-113 ◽  
Author(s):  
Laurence Irving ◽  
H.C. Foster ◽  
J.K.W. Ferguson
Keyword(s):  
Carbon Dioxide ◽  
Dissociation Curve ◽  
Mammalian Muscle ◽  
Carbon Dioxide Dissociation Curve

The in vivo carbon dioxide dissociation curve of true plasma

1966 ◽  
Vol 1 (2) ◽  
pp. 121-137 ◽  
Author(s):  
C.C. Michel ◽  
B.B. Lloyd ◽  
D.J.C. Cunningham
Keyword(s):  
Carbon Dioxide ◽  
Dissociation Curve ◽  
Carbon Dioxide Dissociation Curve

Quantitation of superoxide generation and substrate utilization by vascular NAD(P)H oxidase

2002 ◽  
Vol 282 (2) ◽  
pp. H466-H474 ◽  
Author(s):  
Heraldo P. Souza ◽  
Xiaoping Liu ◽  
Alexandre Samouilov ◽  
Periannan Kuppusamy ◽  
Francisco R. M. Laurindo ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Spin Trapping ◽  
Superoxide Generation ◽  
Substrate Consumption ◽  
Similar Time ◽  
Paramagnetic Resonance ◽  
Resonance Spin ◽  
Electron Paramagnetic

In vascular tissues, an NAD(P)H oxidase is the main source of superoxide; however, there has been much uncertainty regarding its activity and the levels of superoxide it generates. This problem has limited overall progress in this field. Therefore, studies were performed and techniques developed to quantitatively assess the function of the vascular NAD(P)H oxidase, measuring its rate of superoxide production and substrate consumption in rat aortic homogenates and intact segments. NADPH/NADH oxidation was measured spectrophotometrically, and oxygen consumption was measured by electrochemical probe. Superoxide was detected and quantitated by electron paramagnetic resonance spin trapping. Under basal conditions, superoxide generation and oxygen consumption were negligible. After addition of NADPH or NADH (0.1 mM), superoxide was generated at rates of 0.41 ± 0.03 or 0.36 ± 0.04 nmol · mg protein−1· min−1, respectively. Oxygen was consumed with a similar time course at rates of 1.5 ± 0.2 or 1.3 ± 0.3 nmol · mg protein−1· min−1, and NADPH or NADH were oxidized at rates of 1.8 ± 0.4 and 1.5 ± 0.3 nmol · mg protein−1· min−1, respectively. In intact aortic rings, superoxide was generated with rates of 4.0 ± 0.7 or 3.7 ± 0.7 pmol · mg tissue−1· min−1, whereas oxygen was consumed at rates of 22.1 ± 5.0 or 14.5 ± 3.3 pmol · mg tissue−1· min−1, for NADPH or NADH, respectively. These values are lower than those previously measured using lucigenin, which uncouples flavoenzymes, triggering additional superoxide generation. This quantitative approach for characterization of the vascular NAD(P)H oxidase activity should facilitate the further identification and cellular characterization of this enzyme(s) and its functional and signaling roles.

scholarly journals Muscular exercise, lactic acid and the supply and utilisation of oxygen.— Parts VII–VIII

1924 ◽  
Vol 97 (682) ◽  
pp. 155-176 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Body Weight ◽  
Lactic Acid ◽  
The Body ◽  
Muscular Exercise ◽  
Oxygen Intake ◽  
Carbon Dioxide Output ◽  
Long Time ◽  
The Times ◽  
Ventilation Of The Lungs

(A) The relation between oxygen intake and severity of exertion . — When muscular exercise commences, the ventilation of the lungs, the oxygen intake and the carbon dioxide output rise rapidly, in a period of about 2½ minutes, to values characteristic of the severity of the exercise; at these values they remain approximately constant. If the exercise be moderate, i. e ., if the oxygen intake does not approach the maximum for the subject investigated, then the exercise may be continued for a long time: the body is able, so to speak, to provide the energy required “out of income.” If, however, the effort be excessive, the condition of exercise is not stable, the ventilation, the oxygen intake and the carbon dioxide output tend to attain their maximum values, and fatigue and exhaustion gradually or rapidly set in. The relation between these quantities and the magnitude of the effort made is clearly shown in Table I, especially in the series of 14 experiments made on A. V. H. running; at speeds from 2·86 to 4·7 metres per second. These results are plotted as double circles in fig. 1; the other points shown are the results obtained with S., W., and J. (who have approximately the same body-weight and build as A. V. H.), and with C. N. H. L. and H. L. (who are lighter). The observations on the two latter have been “reduced” to the same body-weight as A. V. H. before plotting. The running was on an open-air grass track, about 90 metres round, the speed being kept constant by an observer calling the times of successive laps. In every case the collection of expired gases was preceded by a sufficient foreperiod of exercise (2½ minutes or more) to ensure that a steady condition was reached. The following conclusions may be drawn from these observations:— (1) At low speeds the ventilation is small and the respiratory quotient is low: the oxygen supply is adequate to the needs of the body, lactic acid does not accumulate, and a steady state is soon attained.

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