INVESTIGADORES
TORIANO Roxana Mabel
artículos
Título:
Spontaneous water secretion in T84 cells: effects of STa enterotoxin, bumetanide, VIP, forskolin, and A-23187
Autor/es:
TORIANO ROXANA; KIERBEL ARLINET; RAMIREZ MARCO ANTONIO; MALNIC GERHARD; PARISI MARIO
Revista:
AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY
Editorial:
AMER PHYSIOLOGICAL SOC
Referencias:
Año: 2001 vol. 281 p. 816 - 822
ISSN:
0193-1857
Resumen:
The regulated Cl secretory apparatus of T84 cells responds to several pharmacological agents via different second messengers (Ca2+, cAMP, cGMP). However, information about water movements in T84 cells has not been available. In the absence of osmotic or chemical gradient, we observed a net secretory transepithelial volume flux (Jw = 0.16 ± 0.02 µl · min1 · cm2) in parallel with moderate short-circuit current values (Isc = 1.55 ± 0.23 µA/cm2). The secretory Jw reversibly reverted to an absorptive value when A-23187 was added to the serosal bath. Vasoactive intestinal polypeptide increased Isc, but, unexpectedly, Jw was not affected. Bumetanide, an inhibitor of basolateral Na+-K+-2Cl cotransporter, completely blocked secretory Jw with no change in Isc. Conversely, serosal forskolin increased Isc, but Jw switched from secretory to absorptive values. Escherichia coli heat-stable enterotoxin increased secretory Jw and Isc. No difference between the absorptive and secretory unidirectional Cl fluxes was observed in basal conditions, but after STa stimulation, a significant net secretory Cl flux developed. We conclude that, under these conditions, the presence of secretory or absorptive Jw values cannot be shown by Isc and ion flux studies. Furthermore, RT-PCR experiments indicate that aquaporins were not expressed in T84 cells. The molecular pathway for water secretion appears to be transcellular, moving through the lipid bilayer or, as recently proposed, through water-solute cotransporters. water-ion permeability; chloride secretion; aquaporins; water-solute cotransport; heat-stable enterotoxin; vasoactive intestinal peptide