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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1990 Jul;87(13):4956–4960. doi: 10.1073/pnas.87.13.4956

Separate Cl- conductances activated by cAMP and Ca2+ in Cl(-)-secreting epithelial cells.

W H Cliff 1, R A Frizzell 1
PMCID: PMC54240  PMID: 2164213

Abstract

We studied the cAMP- and Ca2(+)-activated secretory Cl- conductances in the Cl(-)-secreting colonic epithelial cell line T84 using the whole-cell patch-clamp technique. Cl- and K+ currents were measured under voltage clamp. Forskolin or cAMP increased Cl- current 2-15 times with no change in K+ current. The current-voltage relation for cAMP-activated Cl- current was linear from -100 to +100 mV and showed no time-dependent changes in current during voltage pulses. Ca2+ ionophores or increased pipette Ca2+ increased both Cl- and K+ currents 2-30 times. The Ca2(+)-activated Cl- current was outwardly rectified, activated during depolarizing voltage pulses, and inactivated during hyperpolarizing voltage pulses. Addition of ionophore after forskolin further increased Cl- conductance 1.5-5 times, and the current took on the time-dependent characteristics of that stimulated by Ca2+. Thus, cAMP and Ca2+ activate Cl- conductances with different properties, implying that these second messengers activate different Cl- channels or that they induce different conductive and kinetic states in the same Cl- channel.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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