Validation of a Simplified, Portable Cardiopulmonary Gas Exchange System for Submaximal Exercise Testing~!2009-10-25~!2010-01-09~!2010-03-17~!

We tested the effect of daytime chronic moderate ozone (O3) exposure, short-term acute exposure, and both chronic and acute O3exposure combined on nocturnal transpiration in California black oak and blue oak seedlings. Chronic O3exposure (70 ppb for 8 h/day) was implemented in open-top chambers for either 1 month (California black oak) or 2 months (blue oak). Acute O3exposure (~1 h in duration during the day, 120–220 ppb) was implemented in a novel gas exchange system that supplied and maintained known O3concentrations to a leaf cuvette. When exposed to chronic daytime O3exposure, both oaks exhibited increased nocturnal transpiration (without concurrent O3exposure) relative to unexposed control leaves (1.8× and 1.6×, black and blue oak, respectively). Short-term acute and chronic O3exposure did not further increase nocturnal transpiration in either species. In blue oak previously unexposed to O3, short-term acute O3exposure significantly enhanced nocturnal transpiration (2.0×) relative to leaves unexposed to O3. California black oak was unresponsive to (only) short-term acute O3exposure. Daytime chronic and/or acute O3exposures can increase foliar water loss at night in deciduous oak seedlings.

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Analysis of the gas exchange system dynamics during high-frequency ventilation

Annals of Biomedical Engineering ◽

10.1007/bf02484470 ◽

1986 ◽

Vol 14 (6) ◽

pp. 525-542 ◽

Cited By ~ 6

Author(s):

S. D. Ghazanshahi ◽

V. Z. Marmarelis ◽

S. M. Yamashiro

Keyword(s):

Gas Exchange ◽

System Dynamics ◽

High Frequency ◽

High Frequency Ventilation ◽

Exchange System ◽

Frequency Ventilation ◽

Gas Exchange System

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Regulation of Carboxylation and Photosynthetic Oscillations During Sun-Shade Acclimation in Helianthus annuus Measured With a Rapid-Response Gas Exchange System

Functional Plant Biology ◽

10.1071/pp9880239 ◽

1988 ◽

Vol 15 (2) ◽

pp. 239 ◽

Cited By ~ 8

Author(s):

CB Osmond ◽

V Oja ◽

A Laisk

Keyword(s):

Gas Exchange ◽

Intercellular Co2 Concentration ◽

Photosynthetic Apparatus ◽

Co2 Concentration ◽

Rapid Response ◽

Exchange System ◽

Dynamic Regulation ◽

Bisphosphate Carboxylase ◽

Shade Acclimation ◽

Gas Exchange System

The consequences of acclimation from shade to sun and vice versa for regulated photosynthetic metabolism were examined in H. annuus. A rapid-response gas exchange system was used to assess changes in carboxylation-related parameters (mesophyll conductance, assimilatory charge and CO2 capacity) and to analyse oscillations in CO2 fixation following transfer to high CO2 concentration as a function of intercellular CO2 concentration and light intensity. Data showed a two- to threefold change in all carboxylation-related parameters during acclimation in either direction. Dynamic regulation of carboxylation, indicated by changes in oscillatory response as a function of CO2 concentration at light saturation, remained unchanged, consistent with concerted regulation of ribulose-1,5-bisphosphate carboxylase-oxygenase during acclimation. However, the light dependency of oscillations changed during acclimation from shade to sun, and the range of oscillation was closely tied to the maximum rate of steady-state photosynthesis at CO2 saturation. These data imply that changes in the light-absorbing and electron transport components of the photosynthetic apparatus underlie the shift in regulatory behaviour during acclimation.

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Gas-blood PCO2 gradients during avian gas exchange

Journal of Applied Physiology ◽

10.1152/jappl.1975.39.3.405 ◽

1975 ◽

Vol 39 (3) ◽

pp. 405-410 ◽

Cited By ~ 20

Author(s):

D. G. Davies ◽

R. E. Dutton

Keyword(s):

Gas Exchange ◽

Exchange System ◽

Arterial Pco2 ◽

Charged Membrane ◽

Venous Pco2 ◽

Avian Lung ◽

Gas Exchange System ◽

Spontaneously Breathing ◽

Membrane Mechanism ◽

Mixed Venous

The avian respiratory system is a crosscurrent gas exchange system. One of the aspects of this type of gas exchange system is that end-expired PCO2 is greater than arterial PCO2, the highest possible value being equal to mixed venous PCO2. We made steady-state measurements of arterial, mixed venous, and end-expired PCO2 in anesthetized, spontaneously breathing chickens during inhalation of room air or 4–8% CO2. We found end-expired PCO2 to be higher than both arterial and mixed venous PCO2, the sign of the differences being such as to oppose passive diffusion. The observation that end-expired PCO2 was higher than arterial PCO2 can be explained on the basis of crosscurrent gas exchange. However, the observation that end-expired PCO2 exceeded mixed venous PCO2 must be accounted for by some other mechanism. The positive end-expired to mixed venous PCO2 gradients can be explained if it is postulated that the charged membrane mechanism suggested by Gurtner et al. (Respiration Physiol. 7: 173–187, 1969) is present in the avian lung.

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