Endothelin-induced biphasic formation of 1,2-diacylglycerol in cultured rabbit vascular smooth muscle cells--mass analysis with a radioenzymatic assay.
Mass analysis of 1,2-diacylglycerol (DG) with a radioenzymatic assay revealed that endothelin induced a biphasic formation of DG with an early transient phase peaking at 30 sec and a late sustained phase peaking at 5 min in cultured rabbit vascular smooth muscle cells (VSMCs). The amounts of DG after the 30-sec and 5-min incubation with endothelin were 0.74 +/- 0.08 (mean +/- SE) nmol and 0.87 +/- 0.10 nmol/100 nmol of lipid phosphorus, representing 2.6- and 3.1-fold increases of the resting level, respectively. The EC50 values of endothelin for the early and late phases of DG formation were about 1 nM and 40 nM, respectively. In the [3H] inositol-labeled VSMCs, endothelin induced a rapid transient formation of inositol tris- and bisphosphates which peaked at 30 sec and a sustained formation of inositol monophosphate which peaked at 5 min. The EC50 values for the formation of these inositol phosphates were the same and about 1 nM. These results suggest that the early transient phase of DG is derived from the hydrolysis of polyphosphoinositides, while a large part of the late sustained phase of DG is from the reaction(s) other than the hydrolysis of phosphoinositides but its sources remain to be clarified.
Sunako
M
M
Department of Internal Medicine, Kobe University School of Medicine, Japan.
Kawahara
Y
Y
Kariya
K
K
Araki
S
S
Fukuzaki
H
H
Takai
Y
Y
D000818:Animals; D002478:Cells, Cultured; D019852:Diacylglycerol Kinase; D004075:Diglycerides / Q000032:analysis / Q000096:biosynthesis*; D016232:Endothelins; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D005989:Glycerides / Q000096:biosynthesis*; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism; D007668:Kidney; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism; D010770:Phosphotransferases / Q000032:analysis; D011817:Rabbits; D051381:Rats
C011439:1,2-diacylglycerol; D004075:Diglycerides; D016232:Endothelins; D005989:Glycerides; D007295:Inositol Phosphates; D010455:Peptides; D010716:Phosphatidylinositols; C051854:inositol 3,4-bisphosphate; D015544:Inositol 1,4,5-Trisphosphate; D010770:Phosphotransferases; D019852:Diacylglycerol Kinase