ISSN:
1432-0878
Keywords:
Intestine
;
Sodium transport
;
Enterocyte
;
Plasma membranes
;
Stereology
;
Biochemistry
;
Cytochemistry
;
Domestic fowl
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The coprodaeum of the domestic hen maintained on a low-NaCl diet adapts by enhanced sodium transport. This study examines the adaptive response at the single cell and whole organ levels. Surface areas of apical (microvillous) and basolateral plasma membranes of columnar absorptive epithelial cells were estimated by use of ultrastructural stereology. The activities of succinic dehydrogenase (a mitochondrial enzyme) and ouabain-sensitive, potassium-dependent paranitrophenyl phosphatase (a sodium pump enzyme) were determined in tissue homogenates. Sodium, potassium-ATPase (pump enzyme) activity in cell membranes was localized by ultrastructural cytochemistry. Apical and basolateral membranes responded differently. In high-NaCl hens, the membrane signature of the average cell was 32 μm2 (apical), 932 μm2 (lateral) and 17 μm2 (basal). Cells from low-NaCl hens had more apical membrane (49 μm2 per cell) but essentially the same area of basolateral membrane. However, total surfaces per organ were greater for all membranes. Sodium pump enzymes were localized in basolateral membranes. Enzyme activities per unit mitochondrial volume and per unit basolateral membrane surface were higher in low-NaCl birds. These findings are discussed in the context of known mechanisms of transcellular sodium transport via apical ion channels and basolateral pumps.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00645061
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