Characteristics of transport processes involved in ischemia and reperfusion

Author(s):  
H. Kammermeier
1994 ◽  
Vol 77 (3) ◽  
pp. 1116-1121 ◽  
Author(s):  
P. L. Khimenko ◽  
J. W. Barnard ◽  
T. M. Moore ◽  
P. S. Wilson ◽  
S. T. Ballard ◽  
...  

To determine the role of various Na+ transport systems in the edema fluid accumulation after ischemia and reperfusion in the lung, we evaluated the effect of amiloride (a Na+ channel blocker), ouabain (a Na(+)-K(+)-adenosinetriphosphatase blocker), and phloridzin (a Na(+)-glucose cotransport blocker) in isolated rat lungs. Ischemia and reperfusion (I/R) significantly increased the edema accumulation, with the wet-to-dry weight ratios increasing to 10.14 +/- 0.58 from 6.03 +/- 0.05 in control lungs (P < 0.04). Amiloride significantly augmented the amount of edema fluid (wet-to-dry weight ratio 12.26 +/- 0.77), and ouabain further increased the amount of edema (wet-to-dry weight ratio 18.58 +/- 1.00). Phloridzin did not significantly affect edema formation associated with I/R. Isoproterenol decreased the amount of edema formation in the presence and absence of amiloride. This occurred because the endothelial permeability as assessed by filtration coefficient was restored to normal values and less edema formed. The present study indicates that Na+ channels and Na(+)-K(+)-adenosinetriphosphatase, components of the active Na+ absorption transport system, are very important in opposing edema fluid accumulation in rat lungs subjected to I/R injury and operate as an edema safety factor. However, if the endothelial damage associated with I/R is allowed to persist, then the transport processes, even if operative, are insufficient to prevent continuous edema accumulation.


1984 ◽  
Vol 75 ◽  
pp. 597
Author(s):  
E. Grün ◽  
G.E. Morfill ◽  
T.V. Johnson ◽  
G.H. Schwehm

ABSTRACTSaturn's broad E ring, the narrow G ring and the structured and apparently time variable F ring(s), contain many micron and sub-micron sized particles, which make up the “visible” component. These rings (or ring systems) are in direct contact with magnetospheric plasma. Fluctuations in the plasma density and/or mean energy, due to magnetospheric and solar wind processes, may induce stochastic charge variations on the dust particles, which in turn lead to an orbit perturbation and spatial diffusion. It is suggested that the extent of the E ring and the braided, kinky structure of certain portions of the F rings as well as possible time variations are a result of plasma induced electromagnetic perturbations and drag forces. The G ring, in this scenario, requires some form of shepherding and should be akin to the F ring in structure. Sputtering of micron-sized dust particles in the E ring by magnetospheric ions yields lifetimes of 102to 104years. This effect as well as the plasma induced transport processes require an active source for the E ring, probably Enceladus.


1982 ◽  
Vol 43 (C9) ◽  
pp. C9-369-C9-380 ◽  
Author(s):  
A. R. Cooper ◽  
Jr
Keyword(s):  

2018 ◽  
Vol 106 (1) ◽  
pp. 107 ◽  
Author(s):  
Jean- Louis Crolet

All that was said so far about passivity and passivation was indeed based on electrochemical prejudgments, and all based on unverified postulates. However, due the authors’ fame and for lack of anything better, the great many contradictions were carefully ignored. However, when resuming from raw experimental facts and the present general knowledge, it now appears that passivation always begins by the precipitation of a metallic hydroxide gel. Therefore, all the protectiveness mechanisms already known for porous corrosion layers apply, so that this outstanding protectiveness is indeed governed by the chemistry of transport processes throughout the entrapped water. For Al type passivation, the base metal ions only have deep and complete electronic shells, which precludes any electronic conductivity. Then protectiveness can only arise from gel thickening and densification. For Fe type passivation, an incomplete shell of superficial 3d electrons allows an early metallic or semimetallic conductivity in the gel skeleton, at the onset of the very first perfectly ordered inorganic polymers (- MII-O-MIII-O-)n. Then all depends on the acquisition, maintenance or loss of a sufficient electrical conductivity in this Faraday cage. But for both types of passive layers, all the known features can be explained by the chemistry of transport processes, with neither exception nor contradiction.


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