The blood transfer conductance for CO and NO

2017 ◽  
Vol 241 ◽  
pp. 53-57 ◽  
Author(s):  
Colin Borland ◽  
J Michael B Hughes ◽  
Hervé Guénard
Keyword(s):  
Transfer Conductance

Effects of leaf age on internal CO2 transfer conductance and photosynthesis in tree species having different types of shoot phenology

2001 ◽  
Vol 28 (11) ◽  
pp. 1075 ◽  
Author(s):  
Yuko T. Hanba ◽  
Shin-Ichi Miyazawa ◽  
Hiroyuki Kogami ◽  
Ichiro Terashima
Keyword(s):  
Tree Species ◽  
Leaf Age ◽  
High Irradiance ◽  
Deciduous Tree ◽  
Mesophyll Cells ◽  
Different Types ◽  
Internal Co2 ◽  
Transfer Conductance ◽  
Shoot Phenology ◽  
Acer Mono

We examined the changes in leaf anatomy and some physiological characteristics during leaf expansion and maturation. Three deciduous tree species having different types of shoot phenology, maple (Acer mono Maxim.; ‘flush’ type), alder (Alnus japonica(Thunb.) Steud.; ‘successive’ type), and Japanese poplar (Populus maximowiczii A. Henry; ‘successive’ type), were studied. Leaf CO 2 assimilation rate at high irradiance (P max) and CO 2 transfer conductance inside the leaf (g i) varied significantly with leaf development. There were strong positive relationships between P max) and g i for all of the species. The variations in g i were partly related to those in the surface area of chloroplasts facing the intercellular airspaces, while some other factors that related to liquid phase conductance may also contribute to the variation in g i . The developments of mesophyll cells were accompanied by the concomitant increase in chloroplast and Rubisco content in Alnus and Populus (successive types).

Factors affecting gas transfer in respiratory organs of vertebrates

1989 ◽  
Vol 67 (12) ◽  
pp. 2956-2960 ◽  
Author(s):  
Johannes Piiper
Keyword(s):  
Gas Exchange ◽  
Carbonic Acid ◽  
Exchange Process ◽  
Gas Transfer ◽  
Relative Role ◽  
Factors Affecting ◽  
Pulmonary Capillary Blood ◽  
D Values ◽  
Transfer Conductance ◽  
Respiratory Gases

The ability of a gas-exchange organ to transfer respiratory gases (O2 and CO2) between the respiratory medium (air or water) and blood is quantitatively characterized by its transfer conductance, usually termed diffusing capacity, D. The problems in defining and determining D are reviewed. In a blood-perfused gas-exchange organ it is useful to consider the ratio [Formula: see text] ([Formula: see text], blood flow; β, effective solubility) which determines the relative role of diffusion limitation. Poor gas transfer may be due to functional inhomogeneities, and not to low D values. Besides the well-known ventilation–perfusion inequality, other types of inhomogeneity involving diffusion resistances in the medium may be operative. Determination of D in functionally inhomogeneous gas-exchange organs is difficult because of both modeling and measurement problems. In blood to medium transfer of CO2, particular features have been noted. First, the equilibration of CO2 between medium and blood appears to be slower than expected on the basis of high physical solubility, owing to the slowness of some steps in the CO2 exchange process (dehydration of carbonic acid, bicarbonate–chloride exchange of red cells). Second, there is controversial evidence for equilibration of pulmonary capillary blood to a CO2 partial pressure lower than that in lung gas.

Kinetics of O2 uptake and release by human erythrocytes studied by a stopped-flow technique

1985 ◽  
Vol 58 (4) ◽  
pp. 1215-1224 ◽  
Author(s):  
K. Yamaguchi ◽  
D. Nguyen-Phu ◽  
P. Scheid ◽  
J. Piiper
Keyword(s):  
Time Course ◽  
External Medium ◽  
Human Erythrocytes ◽  
Stopped Flow ◽  
Diffusion Limitation ◽  
O2 Uptake ◽  
Intracellular Diffusion ◽  
Transfer Conductance ◽  
Kinetics Of ◽  
Uptake And Release

The kinetics of O2 uptake into and release from human erythrocytes was investigated at 37 degrees C by a stopped-flow technique. From the time course of O2 saturation (SO2) change a specific transfer conductance of erythrocytes for O2 (GO2) was calculated. The following results were obtained: 1) GO2 decreased in the course of O2 uptake, but initial GO2 was nearly independent of SO2 at which uptake started; 2) addition of albumin to the medium reduced GO2; 3) increasing dithionite concentration in the medium in O2-release experiments progressively enhanced GO2, which became virtually constant for nearly the entire course of release; and 4) O2 uptake and O2 release (without dithoite) in the same SO2 range yielded very similar GO2. These results suggested that O2 uptake and release were importantly limited by diffusion through the external medium and that in the SO2 range between 0.3 and 0.8, chemical reaction exerted little limiting effect. Since O2 release at the highest dithionite concentration (40 mmol/l) appeared to be virtually unlimited by external diffusion, GO2 measured under these conditions, averaging 8.7 ml X min-1 X Torr-1 X ml erythrocytes-1, was considered to mainly reflect intracellular diffusion limitation. The corresponding specific transfer conductance for O2 transfer in whole blood (hematocrit, 0.45) is 3.9 ml X min-1 X Torr-1 X ml blood-1.

scholarly journals The blood transfer conductance for nitric oxide: Infinite vs. finite θ NO

2017 ◽  
Vol 241 ◽  
pp. 45-52 ◽  
Author(s):  
Kirsten E. Coffman ◽  
Steven C. Chase ◽  
Bryan J. Taylor ◽  
Bruce D. Johnson
Keyword(s):  
Nitric Oxide ◽  
Transfer Conductance
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