Human alpha-thrombin induces phosphoinositide turnover and Ca2+ movements in cultured human umbilical vein endothelial cells.
This report shows that purified human alpha-thrombin was able to stimulate a rapid and transient formation of water-soluble phosphorylated 3H-inositols in cultured human umbilical vein endothelial cells (HUVEC) prelabelled with 3H-inositol. A parallel breakdown and resynthesis of 3H-inositol-containing phospholipids was observed. Simultaneously, thrombin induced a transient increase of intracellular free Ca2+[( Ca2+]i), as measured from increased fluorescence of quin2 loaded cells. Phosphoinositide turnover and Ca2+ mobilization showed a similar dependence on thrombin dose. [Ca2+]i rise resulted from both influx from extracellular medium and redistribution from intracellular storage sites. On the other hand thrombin-induced phosphoinositide hydrolysis was not dependent on [Ca2+]i rise. [Ca2+]i elevation might be, at least partially, a consequence of increased phosphoinositide turnover, as suggested by [Ca2+]-mobilizing activity of inositol-trisphosphate in other cells.
Lampugnani
M G
MG
Istituto Mario Negri, Milano, Italy.
Pedehovi
M
M
Dejana
E
E
Rotilio
D
D
Donati
M B
MB
Bussolino
F
F
Garbarino
G
G
Ghigo
D
D
Bosia
A
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004533:Egtazic Acid; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D004987:Ethers / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D015759:Ionomycin; D010716:Phosphatidylinositols / Q000378:metabolism* / Q000502:physiology; D013917:Thrombin / Q000502:physiology*; D014471:Umbilical Veins / Q000166:cytology / Q000378:metabolism* / Q000502:physiology
D000900:Anti-Bacterial Agents; D004987:Ethers; D010716:Phosphatidylinositols; D004533:Egtazic Acid; D015759:Ionomycin; D013917:Thrombin; D002118:Calcium