Prostaglandin E1 activates a chloride current in Jurkat T lymphocytes via cAMP-dependent protein kinase.
Patch-clamp studies have identified a cAMP-dependent Cl- conductance in lymphocytes that is defectively regulated in cystic fibrosis. In this study we used 125I efflux and whole-cell patch-clamp studies to investigate whether prostaglandin E1 (PGE1), an agonist that generates intracellular cAMP in Jurkat T lymphocytes, activates a Cl- conductance. Stimulation of T cells by externally applied PGE1 stimulated 125I efflux and activated a slowly developing membrane current. When external and internal Cl- were about equal, the current reversed at about zero mV, but when external Cl- was lowered from 157 to 7 mM the reversal potential shifted 75 mV in the positive direction, demonstrating that the current carrier was Cl-. In addition, the current was blocked by 10 microM 5-nitro-2(3-phenylpropylamino) benzoic acid (NPPB), a potent Cl- channel blocker. A membrane-permeable cAMP analog mimicked the effect of PGE1, whereas intracellular application of a cAMP antagonist Rp-cAMP blocked the effect of PGE1. Addition of purified catalytic subunit of cAMP-dependent protein kinase (PKA) plus ATP to the recording pipette also activated a similar current, whereas internally applied Walsh inhibitor, the synthetic peptide inhibitor of PKA, blocked the PGE1 effect. These results suggest that PGE1, acting through PKA, activates a Cl- current in Jurkat T cells.
Maldonado
D
D
Department of Medicine, Falk Cardiovascular Research Center, Stanford University School of Medicine, California.
Schumann
M
M
Nghiem
P
P
Dong
Y
Y
Gardner
P
P
D000527:Alprostadil / Q000494:pharmacology*; D002460:Cell Line; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects*; D008565:Membrane Proteins / Q000187:drug effects* / Q000378:metabolism; D011494:Protein Kinases / Q000187:drug effects / Q000502:physiology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D018118:Chloride Channels; D002712:Chlorides; D007473:Ion Channels; D008565:Membrane Proteins; D011494:Protein Kinases; D000527:Alprostadil