Stretch-induced morphological changes of human endothelial cells depend on the intracellular level of Ca2+ rather than of cAMP.
When exposed to a uni-axial cyclic stretch, cultured human umbilical vein endothelial cells (HUVECs) align and elongate perpendicular to the stretch axis. Previous studies showed that forskolin inhibited stretch-induced orientation of endothelial cells, suggesting that adenosine 3:5-cyclic monophosphate (cAMP) plays an important role in the shape change. However, we have recently shown that stretch-induced shape changes in cultured HUVECs are due to increased [Ca2+]i. In the present study, we examined the possible role of cAMP in stretch-induced shape changes in cultured HUVECs. Application of uni-axial cyclic stretch induced a gradual rise in cAMP reaching a peak level at 60 min after the onset of stretch. The adenylate cyclase activator, forskolin, increased the basal level of cAMP but inhibited the rise in [Ca2+]i resulting in no cell shape changes. In contrast, N 6,2-dibutyryladenosine 3:5-cyclic monophosphate (dbcAMP) enhanced the stretch-induced increase in cAMP and [Ca2+]i and resulted in cell shape changes. On the other hand, 2'5'-dideoxyadenosine (DDA), an adenylate cyclase inhibitor, inhibited stretch-induced increases in cAMP and [Ca2+]i resulting in no cell shape changes. In summary, our data showed that cell shape changes were consistently dependent on [Ca2+]i rather than cAMP levels. We conclude that the primary second messenger in the stretch-induced shape changes in HUVECs is intracellular Ca2+ rather than cAMP.
Yamada
T
T
Department of Physiology, Nagoya University, School of Medicine, Japan.
Naruse
K
K
Sokabe
M
M
D000067956:Adenylyl Cyclase Inhibitors; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D016048:Dideoxyadenosine / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007231:Infant, Newborn; D013314:Stress, Mechanical; D014471:Umbilical Veins / Q000166:cytology
D000067956:Adenylyl Cyclase Inhibitors; D004791:Enzyme Inhibitors; D005576:Colforsin; D016048:Dideoxyadenosine; D003994:Bucladesine; D000242:Cyclic AMP; D002118:Calcium