Ba2+ inhibition of VIP- and A23187-stimulated Cl- secretion by T84 cell monolayers
Addition of either 10(-8) M vasoactive intestinal polypeptide (VIP) or 10(-6) M A23187 to T84 cell monolayers, grown on permeable supports and mounted in Ussing chambers, stimulated net Cl- secretion. The effect of 10(-6) M A23187 on Cl- flux was consistently smaller than that observed with 10(-8) M VIP. In both cases the increase in net Cl- secretion accounted for the entire change in the observed short-circuit current (Isc). Since Cl- enters the cells through a basolaterally localized Na+-K+-Cl(-)-cotransport system (J. Clin. Invest. 75: 462, 1985), the fate of K+, which is cotransported with Cl- during VIP, and A23187-mediated Cl- secretion was explored. Unidirectional and net transepithelial 42K+ flux rates were negligible compared with 36Cl- flux rates (less than 4% of Cl- flux), indicating that little K+ was secreted along with Cl-. K+ recycling across the basolateral membrane was suggested from experiments in which 86Rb+ efflux (as a tracer for K+) was measured across the apical and basolateral membranes of 86Rb+ -preloaded monolayers under voltage-clamped conditions. In the absence of secretagogues, 86Rb+ efflux was 10-fold higher across the basolateral membrane than across the apical membrane. 86Rb+ efflux across the basolateral membrane was accelerated two- to threefold by addition of either VIP or A23187. In each case accelerated efflux was inhibited by 5 mM Ba2+. Cl- secretion induced by VIP or A23187 was also inhibited by serosal addition of Ba2+.
- Research Organization:
- Univ. of California, San Diego
- OSTI ID:
- 5739291
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States); ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ALKALI METALS
ALKALINE EARTH METALS
BARIUM
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHLORIDES
CHLORINE COMPOUNDS
DAYS LIVING RADIOISOTOPES
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MEMBRANE TRANSPORT
METALS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
POTASSIUM
RADIOISOTOPES
RUBIDIUM 86
RUBIDIUM ISOTOPES
SECRETION
SODIUM
TRACER TECHNIQUES