Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Prostaglandin E1 activates a chloride current in Jurkat T lymphocytes via cAMP-dependent protein kinase. 172 93

The apical membrane of renal epithelial A6 cells has 3 and 8 pS Cl- channels. Both types of the channels were blocked by NPPB (5-Nitro-2-(3-phenylpropylamino)-benzoic acid; 100 microM). 8-bromo-cAMP (Br-cAMP) increased the open probability of 3 pS Cl- channel and this action was inhibited by pretreatment with H89, an inhibitor of cAMP-dependent protein kinase (PKA). On the other hand, the number of 8 pS Cl- channel was increased by Br-cAMP. The increase in number of 8 pS Cl- channel by Br-cAMP was inhibited by brefeldin A (a blocker of movement of membrane protein from an intracellular pool to the cell surface) but not by H89. These observations indicate that cAMP could activate the 3 pS Cl- channel through PKA-dependent phosphorylation, and that cAMP could stimulate translocation of the 8 pS Cl- channel through PKA-independent pathways. We conclude that PKA-independent pathways are involved in cAMP signaling mechanisms in addition to PKA-dependent pathways.
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PMID:Regulation of chloride channel trafficking by cyclic AMP via protein kinase A-independent pathway in A6 renal epithelial cells. 867 Feb 65

We studied regulation of Cl- transport by cAMP and Ca2+ in renal epithelial A6 cells. Stimulation of A6 cells by 1 mM 3-isobutyl-1-methylxanthine (IBMX, an inhibitor of phosphodiesterase), which increased cytosolic cAMP, elicited biphasic increases in short-circuit current (Isc), i.e., a transient phase followed by a sustained one. Apical application of 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB, a Cl- channel blocker) markedly and dose-dependently inhibited the IBMX-induced Isc. Pretreatment with nifedipine (100 microM, a Ca2+ channel blocker) or 1,2-bis(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra-(acetoxymethyl)-ester (BAPTA/AM, 10 microM, a Ca2+ chelator) partially but markedly inhibited the Isc. On the other hand, a cAMP-dependent protein kinase inhibitor, H89 (0.5 microM for 1 h), also reduced the IBMX-induced Isc to a level similar to that following nifedipine or BAPTA pretreatment. Nifedipine had no synergistic effects on the IBMX-induced Isc in cells treated with H89. Ionomycin (a Ca2+ ionophore) could mimic the transient increase dose dependently, and H89 did not block the ionomycin-induced Isc. Taken together, our observations suggest that: (1) part of the IBMX-stimulated Cl- release is regulated by an increased cytosolic Ca2+ through nifedipine-sensitive Ca2+ influx; (2) cAMP-dependent phosphorylation may be required for elevation of the cytosolic Ca2+ concentration but not for activation of Cl- channels, which are directly activated by cytosolic Ca2+; and (3) the IBMX-induced sustained Cl- release requires cAMP elevation in addition to an increase in the cytosolic Ca2+ concentration.
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PMID:Regulation of Cl- transport by IBMX in renal A6 epithelium. 917 19

Secretin stimulates bicarbonate secretion from pancreatic duct cells, but what influence secretin exerts on intestinal tissues remains to be clarified. The aim of this study is to examine effects of secretin on ion transport in intestinal epithelial Caco-2 cells. We mounted monolayers of Caco-2 cells grown on permeable supports for 21-28 d in a Ussing chamber and measured short-circuit currents (I(sc)). Addition of secretin (5-100 nM) to the basolateral solution dose-dependently induced biphasic increases of I(sc) (transient and sustained phase). Dibutyryl cyclic AMP (200 microM), forskolin (10 microM), and 3-isobutyl-1-methylxanthine (IBMX, 1 mM) also induced I(sc) responses similar to the administration of secretin. Addition of 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB, 100 microM) or benzamil (100 microM) to the apical solution markedly reduced the secretin-induced I(sc) increase in the transient phase. A selective antagonist of cAMP-dependent protein kinase (PKA), N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89, 1 microM), and a membrane permeable Ca(2+) chelator, 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA/AM, 10 microM) reduced the secretin-induced I(sc). Basolateral addition of 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 1 mM) suppressed the sustained phase I(sc) increase. Secretin also induced alkalinization of the apical solution (DeltapH, 0.053 +/- 0.013). The alkalinization did not occur when DIDS (1 mM) was added to the basolateral solution or Na(+) was removed from the solutions. Taken together, our observations suggest: (1) secretin stimulates a benzamil-sensitive Na(+) influx and an NPPB-sensitive Cl(-) efflux across the apical membrane through PKA-dependent and Ca(2+)-sensitive pathways; and (2) secretin also induces alkalinization of the apical solution through the activation of a DIDS-sensitive Na(+)-HCO(3)(-) cotransport in the basolateral membrane of Caco-2 cells.
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PMID:Activation of transepithelial ion transport by secretin in human intestinal Caco-2 cells. 1088 Aug 78