Activation of diacylglycerol in cultured endothelial cells exposed to cyclic strain.
Confluent bovine aortic endothelial cells (EC) were grown on flexible membranes and subjected to 10% average strain at 60 cycles/min for up to 500 s. A biphasic increase in diacylglycerol (DAG) occurred, with an initial transient peak at 10 s followed by sustained elevation to 500 s. The early peak corresponded to the transient formation of inositol 1,4,5-trisphosphate, demonstrating hydrolysis of L-alpha-phosphatidylinositol (PI) by PI-specific phospholipase C. To determine the origin of the sustained DAG phase, we incubated confluent bovine aortic EC with 1 microCi/ml [14C]myristate overnight and subjected them to cyclic strain. There was a decrease in phosphatidylcholine (PC) and a corresponding increase in DAG at 10 s and 250 s, suggesting PC hydrolysis with the generation of DAG at both an early (10 s) and a late (250 s) phase. [14C]phosphatidylethanol, a specific product of phospholipase D (PLD) in the presence of 1% ethanol, was measured in EC preincubated with [14C]myristate. Cyclic strain led to an immediate and sustained activation of PLD. Increased ethanol concentration led to a consistent decrease in DAG. Furthermore, when EC were pretreated with 1% ethanol, the strain-induced proliferative response was attenuated.
Evans
L
L
Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Frenkel
L
L
Brophy
C M
CM
Rosales
O
O
Sudhaker
C B
CB
Li
G
G
Du
W
W
Sumpio
B E
BE
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004075:Diglycerides / Q000096:biosynthesis*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology; D006868:Hydrolysis; D010507:Periodicity; D010713:Phosphatidylcholines / Q000378:metabolism; D013314:Stress, Mechanical; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors
D004075:Diglycerides; D010713:Phosphatidylcholines; D000431:Ethanol; D013936:Thymidine