Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.21 (CPT)
 4,580 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously we demonstrated that the inner medullary collecting duct cell line mIMCD-K2 secretes Cl- by an electrogenic mechanism [N. L. Kizer, B. Lewis, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F347-F355, 1995; N. L. Kizer, D. Vandorpe, B. Lewis, B. Bunting, J. Russell, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F854-F861, 1995]. The goal of the present study was to characterize the Cl- channel responsible for adenosine 3',5'-cyclic monophosphate (cAMP)-stimulated Cl- secretion. To this end, using the patch-clamp technique, we measured Cl- currents. In whole cell patch-clamp experiments, 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (CPT-cAMP) activated Cl- currents that were time and voltage independent, inhibited by diphenylamine 2-carboxylate (DPC), and had a linear current-voltage (I-V) relation. In cell-attached patches of the apical membrane, we identified 7-pS Cl- channels that were stimulated by CPT-cAMP. In inside-out patches with Cl- in the pipette and bath solutions, Cl- currents had a linear I-V relation. The halide permeability sequence was PCl = PBr > PI. The Cl- channel inhibitors DPC, 5-nitro-2-(3-phenylpropylamino)-benzoic acid, and glibenclamide blocked the 7-pS Cl- channel, whereas 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid was ineffective. By reverse transcriptase polymerase chain reaction, we isolated a partial cDNA clone encoding the cystic fibrosis transmembrane conductance regulator in mIMCD-K2 cells. We conclude that cAMP stimulates electrogenic Cl- secretion in inner medullary collecting duct cells by activating cystic fibrosis transmembrane conductance regulator Cl- channels.
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PMID:CFTR mediates electrogenic chloride secretion in mouse inner medullary collecting duct (mIMCD-K2) cells. 757 98

Previously, we demonstrated that a mouse inner medullary collecting duct cell line (mIMCD-K2) secretes Cl- by an electrogenic mechanism via cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels [N. L. Kizer, B. Lewis, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F347-F355, 1995; N. L. Kizer, D. Vandorpe, B. Lewis, B. Bunting, J. Russell, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F854-F861, 1995; D. Vandorpe, N. Kizer, F. Ciampolillo-Bates, B. Moyer, K. Karlson, W. B. Guggino, and B. A. Stanton. Am. J. Physiol. 269 (Cell Physiol. 38): C683-C689, 1995]. The objective of the present study was to determine whether adenosine, and adenosine A1 receptors (A1AR) specifically, regulate electrogenic Cl- secretion (IscCl) in mIMCD-K2 cells. Neither N6-cyclohexyladenosine (CHA), a specific A1AR agonist, nor 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a specific A1AR antagonist, altered basal, unstimulated IscCl in monolayers of mIMCD-K2 cells mounted in Ussing-type chambers. In contrast, DPCPX increased arginine vasopressin (AVP)-stimulated IscCl, an effect that was reversed by CHA. Adenosine deaminase (ADA), which oxidatively deaminates adenosine to inosine, increased AVP-stimulated IscCl. CHA reversed the stimulatory effect of ADA on AVP-stimulated IscCl. These results suggest that adenosine, via A1AR, inhibits AVP-stimulated IscCl. To identify the source(s) of extracellular adenosine, we examined the effects of dipyridamole, an inhibitor of nucleoside transport, and alpha,beta-methyleneadenosine 5'-diphosphate (AOPCP), an inhibitor of ecto-5'-nucleotidase, on AVP-stimulated IscCl. Both compounds increased AVP-stimulated IscCl. CHA reversed the stimulatory effect of dipyridamole and AOPCP on IscCl. Neither ADA nor CHA had an effect on 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (CPT-cAMP)-stimulated IscCl. Moreover, U-73122, an inhibitor of phospholipase C, failed to attenuate the increase in AVP-stimulated IscCl elicited by dipyridamole and AOPCP or the decrease in AVP-stimulated IscCl elicited by CHA. We conclude that adenosine, released by a nucleoside transporter and formed extracellularly by the breakdown of AMP, binds to A1AR, and decreases AVP-stimulated IscCl in mIMCD-K2 cells by reducing intracellular cAMP levels.
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PMID:Adenosine inhibits arginine vasopressin-stimulated chloride secretion in a mouse IMCD cell line (mIMCD-K2). 859 84