Actions for Action of cholera toxin in the intestinal epithelial cells

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Action of cholera toxin in the intestinal epithelial cells

Author
Hyun, C. S.
Published
United States : [publisher not identified], 1982
Springfield, Va.: National Technical Information Service, [approximately 1982]
Physical Description
microfiche : negative ; 11 x 15 cm

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Summary
The primary event in the action of cholera toxin on the isolated chick intestinal epithelial cell is its interaction with a large number of high affinity binding sites in the cell membrane. Binding of /sup 125/I-labeled toxin is rapid, temperature-dependent, reversible, and saturable over a wide range of concentrations and includes only a small contribution from nonspecific sites. A characteristic lag phase of 10 min occurs following the complete binding of toxin before any increase in cellular cAMP levels can be detected. The response (elevation of cellular cAMP) is linear with time for 40 to 50 min and causes a six- to eight-fold increase over control levels (10 to 15 picomole cAMP/mg cellular protein) at steady state. cAMP and agents that increase cAMP production inhibit Cl/sup -/-independent Na/sup +/ influx into the isolated enterocytes whereas chlorpromazine (CPZ) which completely abolishes toxin-induced elevation of cAMP both reverses and prevents the cAMP-mediated inhibition of Na/sup +/ entry. Correlation between cellular cAMP levels and the magnitude of Na/sup +/ influx provides evidence for a cAMP-mediated control of intestinal Na/sup +/ uptake, which may represent the mechanistic basis for the antiabsorptive effect of CT on Na/sup +/ during induction of intestinal secretion. The effect of cAMP on Na/sup +/ but not Cl/sup -/ influx preparations can be partially explained in terms of a cAMP-regulated Na/sup +//H/sup +/ neutral exchange system. Data on the coupling relationship between Na/sup +/ transport and the intra- and extracellular pH in the enterocytes show that an amiloride-sensitive electroneutral Na/sup +//H/sup +/ exchange process occurs. This coupling between Na/sup +/ and H/sup +/ is partially inhibited by CT and dbcAMP, suggesting that the Na/sup +//H/sup +/ exchange may be a cAMP-regulated process. 31 references, 32 figures, 5 tables.
Report Numbers
DE84016251; DOE/EV/03490-2264
Other Subject(s)
Collection
NTIS collection.
Note
DOE contract number: AC02-76EV03490
OSTI Identifier 6538673
Research organization: Rochester Univ., NY (USA).
View MARC record | catkey: 47343714