ISSN:
1435-5922
Keywords:
stellate cell
;
endothelin
;
fibrosis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract To elucidate the role played by hepatic sinusoidal cells in the regulation of the circulatory status in the liver, the effect of endothelins (ETs) on primarycultured stellate cells was examined. Kinetic analysis with125I-labeled ET-1 revealed that stellate cells have ET receptors with a Kd value of 141 pM and a Bmax of 12.3 fmol/105 cells. ET-1,-2, and-3 dose-dependently increased inositol monophosphate (InsP) levels in stellate cells with an EC50 of 0.53, 1.63, and 1.88 nM, respectively. Binding of125I-labeled ET-1 to stellate cells and the ET-enhanced InsP formation were suppressed by preincubating the cells with 10 nM of unlabeled ET-1 or ET-3 for more than 3 h, indicating down-regulation and desensitization of ET receptors by homologous ligands. Binding of ETs to surface receptors induced a marked contraction of stellate cells. Stellate cells rapidly reacted to ETs, as detected by the flexible silicone-rubber-membrane method; 78%, 73%, and 58% of the stellate cells contracted 2.5 min after the addition of 10 nM of ET-1, ET-2, or ET-3, respectively. On the other hand, ETs also triggered a long-lasting contraction of the cells, as revealed with hydrated collagen gels. The ET-induced contraction of stellate cells decreased the diameter of the collagen lattice by about 60%, and this action was inhibited either by cytochalasin B or by H-7, a protein kinase C inhibitor. These and other results suggest that ETs induced cell contraction by some mechanism that involved protein kinase C.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02349639
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