[Stimulation of ileal transport of calcium by sorbitol in in situ perfused loop in rats].
OBJECTIVE
The aim of this study was to study the effect of sorbitol on sodium, water and calcium fluxes in rat ileum in situ perfused loop.


METHODS
Net water, sodium and calcium fluxes, and one-way calcium fluxes were measured in situ in a perfused rat ileal loop in the presence of varying concentrations of sorbital.


RESULTS
High concentrations of sorbitol in perfused ileal solution induced a decrease of sodium and water fluxes and a concomitant increase of lumen to mucosa calcium flux associated with an increase of net calcium flux, using a solution containing either 8.0 or 1.25 mM calcium. These effects were independent of absolute initial values of water and sodium fluxes. They were observed in the presence of 25 mM glucose, 10 mM theophyllin or after treatment of rats with dexamethasone.


CONCLUSIONS
These effects of sorbitol on calcium flux are not compatible with a stimulation of paracellular pathway. By contrast, they can be explained by a stimulation of transcellular calcium pathway in ileum associated with the hyperpolarisation of the cells induced by the decrease of luminal sodium concentration necessary in the presence of sorbitol to maintain unchanged osmolarity of perfusate.
Auchère
D
D
Laboratoire de Physiologie et Ecole Pratique des Hautes Etudes, Faculté des Sciences Pharmaceutiques et Biologiques, Chatenay-Malabry, France.
Tardivel
S
S
Gounelle
J C
JC
Lacour
B
B
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013012:Sorbitol / Q000494:pharmacology*; D013268:Stimulation, Chemical; D013806:Theophylline / Q000494:pharmacology
D013012:Sorbitol; D003907:Dexamethasone; D013806:Theophylline; D005947:Glucose; D002118:Calcium
Stimulation du transport iléal du calcium par le sorbitol en anse perfusée in situ chez le rat.