This report shows that purified human α-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+]1), as measured from increased fluorescence of quin2 loaded cells. Phosphoinositide turnover and Ca2+ mobilization showed a similar dependence on thrombin dose. [Ca2+]1 rise resulted from both influx from extraceilular medium and redistribution from intracellular storage sites. On the other hand thrombin-induced phosphoinositide hydrolysis was not dependent on [Ca2+]1 rise. [Ca2+]1 elevation might be, at least partially, a consequence of increased phosphoinositide turnover, as suggested by [Ca2+]-mobilizing activity of inositol-trisphosphate in other cells.
- Ca movements
- human umbilical vein endothelial cells
- phosphoinositide turnover
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine