Guanine nucleotide-dependent inhibition of phospholipase C in human endothelial cells.
Treatment of intact human umbilical vein endothelial cells with NaF results in a dose-dependent biphasic response in both prostacyclin and inositol phosphate production: the stimulation observed with 10-20 mM NaF decreases with higher concentrations. High concentrations of NaF furthermore reduce thrombin- or A23187-stimulated prostacyclin production. Direct assay of phospholipase C activity in cell homogenates shows a similar biphasic response to NaF, also after chelation of Ca2+; addition of AlCl3 shifts the inhibition toward lower NaF concentrations. Guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) also causes a dose-dependent biphasic response in inositol phosphate formation in permeabilized cells and homogenates; a higher inhibitory concentration of GTP gamma S abolishes the stimulation of inositol phosphate production by low NaF concentrations. A high concentration of NaF furthermore inhibits the non-G-protein-dependent activation of phospholipase C by deoxycholate. NaF also induces a dose-dependent biphasic response in cyclic AMP formation in intact cells, indicating that the inhibition of phospholipase C at higher NaF concentrations does not result from a rise in cyclic AMP. The data are compatible with the existence of a guanine nucleotide-dependent, cyclic AMP-independent, phospholipase C-inhibitory pathway in endothelial cells.
Center for Thrombosis and Vascular Research, Katholieke Universiteit Leuven, Belgium.
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C
Van Geet
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Deckmyn
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J
Kienast
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C
Wittevrongel
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J
Vermylen
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000535:Aluminum / Q000494:pharmacology; D000077410:Aluminum Chloride; D017607:Aluminum Compounds; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D003840:Deoxycholic Acid / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D011464:Epoprostenol / Q000096:biosynthesis; D006150:Guanine Nucleotides / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D012969:Sodium Fluoride / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors*; D014471:Umbilical Veins
D017607:Aluminum Compounds; D002712:Chlorides; D006150:Guanine Nucleotides; D007295:Inositol Phosphates; D013873:Thionucleotides; D003840:Deoxycholic Acid; D005576:Colforsin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000001:Calcimycin; D000077410:Aluminum Chloride; D006160:Guanosine Triphosphate; D012969:Sodium Fluoride; D000535:Aluminum; D011464:Epoprostenol; D000242:Cyclic AMP; D010738:Type C Phospholipases; D013917:Thrombin; D015056:1-Methyl-3-isobutylxanthine