title: D609-phosphatidylcholine-specific phospholipase C inhibitor attenuates thapsigargin-induced sodium influx in human lymphocytes.
abstract: Previously, we reported that the phosphatidylcholine-specific phospholipase C (PC-PLC) inhibitor tricyclodecan-9-yl xanthogenate (D609) potentiates thapsigargin-induced Ca(2+) influx in human lymphocytes. In the present study we examined the effect of D609 on the thapsigargin-induced Na(+) entry. We found that the early phase of the thapsigargin-induced increase in the intracellular Na(+) concentration (approx. 1-2 min after stimulation) was attenuated after preincubation of lymphocytes with D609. By contrast, thapsigargin-induced Na(+) influx was not affected in the presence butan-1-ol, which inhibits phosphatidylcholine-specific phospholipase D (PC-PLD). The thapsigargin-induced Na(+) influx could be mimicked by PC-PLC exogenously added to the lymphocyte suspension, whereas addition of PC-PLD had no effect. In addition, thapsigargin stimulated formation of the physiological PC-PLC products, diacylglycerol. Cell-permeable diacylglycerol analogue, dioctanoyl-glycerol (DOG), produced time- and concentration-dependent increase in the intracellular Na(+) concentration. Both thapsigargin- and DOG-induced Na(+) increases were not affected in the presence of Na(+)/H(+) antiport inhibitor, HOE609, or Na(+)/Ca(2+) antiport inhibitor, dimethylthiourea, as well as in the presence of Co(2+) and Ni(2+), which block store-operated Ca(2+) entry. By contrast, markedly reduced thapsigargin- and DOG-induced Na(+) influx were noted in the presence of flufenamic acid, which blocks the non-selective cation current (I(CRANC)). In conclusion, our results suggest that diacylglycerol released due to the PC-PLC activation contributes to the thapsigargin-induced Na(+) entry.
authors.affiliation: Institut für Klinische Chemie und Laboratoriumsmedizin, Zentrallaboratorium, Westfälische Wilhelms-Universität, A. Schweitzer Str 33, 48-149, Münster, Germany. nofer@uni-muenster.de
authors.forename: J R
authors.initials: JR
authors.lastname: Nofer
authors.forename: R
authors.initials: R
authors.lastname: Junker
authors.forename: U
authors.initials: U
authors.lastname: Seedorf
authors.forename: G
authors.initials: G
authors.lastname: Assmann
authors.forename: W
authors.initials: W
authors.lastname: Zidek
authors.forename: M
authors.initials: M
authors.lastname: Tepel
mesh_terms: D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D001952:Bridged-Ring Compounds / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D004075:Diglycerides / Q000096:biosynthesis / Q000493:pharmacokinetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000201:enzymology*; D009636:Norbornanes; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology*; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors* / Q000494:pharmacology
chemical_list: D001952:Bridged-Ring Compounds; D004075:Diglycerides; D004791:Enzyme Inhibitors; D009636:Norbornanes; D010726:Phosphodiesterase Inhibitors; D019831:Sodium-Calcium Exchanger; D017923:Sodium-Hydrogen Exchangers; D013859:Thiocarbamates; D013871:Thiones; C044295:1,2-dioctanoylglycerol; C046498:tricyclodecane-9-yl-xanthogenate; D019284:Thapsigargin; D012964:Sodium; D011493:Protein Kinase C; D010738:Type C Phospholipases; C105598:phosphatidylcholine-specific phospholipase C; D010739:Phospholipase D; D002118:Calcium