Localization of carbonic anhydrase in the rat lung

1981 ◽  
Vol 72 (3) ◽  
pp. 415-424 ◽  
Author(s):  
N. Sugai ◽  
Y. Ninomiya ◽  
T. Oosaki
Keyword(s):  
1986 ◽  
Vol 60 (2) ◽  
pp. 638-645 ◽  
Author(s):  
R. P. Henry ◽  
S. J. Dodgson ◽  
R. E. Forster ◽  
B. T. Storey

sCarbonic anhydrase activity in rat lungs perfused free of blood was localized by homogenization of the tissue followed by differential centrifugation. Four fractions were obtained from the homogenate, a cell debris pellet with a mitochondrial pellet and a microsomal pellet with a clear cytosol supernatant. The last named fraction contained 67% of the total enzyme activity; the cell debris contained 18%, and the mitochondrial and microsomal contained 8 and 7%, respectively. Of the 33% of enzyme activity associated with the pellet fraction, 25% could be experimentally defined as membrane associated by its solubilization with 0.3 M tris-(hydroxymethyl) aminoethane sulfate buffer. The remainder was defined as membrane bound. Purification of the soluble carbonic anhydrase from the lung yielded two isozymes with electrophoretic and inhibitor sensitivities apparently identical with the blood isozymes. Hemoglobin analysis showed that the lung isozymes could not have included more than 0.03% enzyme from blood contamination. The carbonic anhydrase activity present in the whole rat lung would give an average acceleration of the CO2 hydration reaction under physiological conditions over the uncatalyzed rate of 122, sufficient to maintain equilibration between CO2 and plasma HCO3- during blood transit of the lung. If the membrane-associated activity is mostly on the plasma membrane of the endothelial cells and available to the capillary blood, it would be sufficient to give this acceleration. We suggest that the possible source of this membrane-associated activity might be adsorption from the blood of carbonic anhydrase liberated by erythrocyte lysis.


1982 ◽  
Vol 52 (2) ◽  
pp. 352-356 ◽  
Author(s):  
G. Lonnerholm

The distribution of carbonic anhydrase in the human, monkey, and rat lung was studied by the histochemical method of Hansson. High activity of this enzyme was demonstrated in the endothelium of pulmonary capillaries. In the human and the monkey lung enzyme activity was exhibited in the whole circumference of the capillaries, but in the rat enzyme activity is confined to capillary segments having close contact with alveolar epithelium forming the blood-air barrier. Staining was inhibited by 10 microM acetazolamide, but was not affected by 10 microM Cl 13,850, an inactive acetazolamide analogue. The location of carbonic anhydrase in the lung supports the idea that pulmonary carbonic anhydrase promotes CO2 elimination from the blood into the alveolar space. Its possible functions may be to act upon plasma to accelerate the conversion of HCO-3 to CO2 and to facilitate CO2 transport through the lung tissue.


Author(s):  
J. A. Nowell ◽  
J. Pangborn ◽  
W. S. Tyler

Leonardo da Vinci in the 16th century, used injection replica techniques to study internal surfaces of the cerebral ventricles. Developments in replicating media have made it possible for modern morphologists to examine injection replicas of lung and kidney with the scanning electron microscope (SEM). Deeply concave surfaces and interrelationships to tubular structures are difficult to examine with the SEM. Injection replicas convert concavities to convexities and tubes to rods, overcoming these difficulties.Batson's plastic was injected into the renal artery of a horse kidney. Latex was injected into the pulmonary artery and cementex in the trachea of a cat. Following polymerization the tissues were removed by digestion in concentrated HCl. Slices of dog kidney were aldehyde fixed by immersion. Rat lung was aldehyde fixed by perfusion via the trachea at 30 cm H2O. Pieces of tissue 10 x 10 x 2 mm were critical point dried using CO2. Selected areas of replicas and tissues were coated with silver and gold and examined with the SEM.


Author(s):  
Judith A. Murphy ◽  
Anthony Paparo ◽  
Richard Sparks

Fingernail clams (Muscu1ium transversum) are dominant bottom-dwelling animals in some waters of the midwest U.S. These organisms are key links in food chains leading from nutrients in water and mud to fish and ducks which are utilized by man. In the mid-1950’s, fingernail clams disappeared from a 100-mile section of the Illinois R., a tributary of the Mississippi R. Some factor(s) in the river and/or sediment currently prevent clams from recolonizing areas where they were formerly abundant. Recently, clams developed shell deformities and died without reproducing. The greatest mortality and highest incidence of shell deformities appeared in test chambers containing the highest proportion of river water to well water. The molluscan shell consists of CaCO3, and the tissue concerned in its secretion is the mantle. The source of the carbonate is probably from metabolic CO2 and the maintenance of ionized Ca concentration in the mantle is controlled by carbonic anhydrase. The Ca is stored in extracellular concentric spherical granules(0.6-5.5μm) which represent a large amount of inertCa in the mantle. The purpose of this investigation was to examine the role of raw river water and well water on shell formation in the fingernail clam.


1955 ◽  
Vol 29 (2) ◽  
pp. 262-279 ◽  
Author(s):  
David A. Dreiling ◽  
Henry D. Janowitz ◽  
Mark Halpern

2004 ◽  
Vol 171 (4S) ◽  
pp. 206-207 ◽  
Author(s):  
Hideki Mukouyama ◽  
Masahiro Yao ◽  
David B. Seligson ◽  
John S. Lam ◽  
Yoji Nagashima ◽  
...  

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