by Keyword: Contraction

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Klein, S., Schierwagen, R., Uschner, F. E., Trebicka, J., (2017). Mouse and rat models of induction of hepatic fibrosis and assessment of portal hypertension Fibrosis (Methods in Molecular Biology) (ed. Rittié, L.), Humana Press (New York, USA) 1627, 91-116

Portal hypertension either develops due to progressive liver fibrosis or is the consequence of vascular liver diseases such as portal vein thrombosis or non-cirrhotic portal hypertension. This chapter focuses on different rodent models of liver fibrosis with portal hypertension and also in few non-cirrhotic portal hypertension models. Importantly, after the development of portal hypertension, the proper assessment of drug effects in the portal and systemic circulation should be discussed. The last part of the chapter is dedicated in these techniques to assess the in vivo hemodynamics and the ex vivo techniques of the isolated liver perfusion and vascular contractility.

Keywords: Aortic ring contraction, Bile duct ligation, Carbon tetrachloride, Colored microsphere technique, High-fat diet, Isolated in situ liver perfusion, Methionine-choline-deficient diet, Partial portal vein ligation, Portal hypertension

Krishnan, Ramaswamy, Klumpers, Darinka D., Park, Chan Y., Rajendran, Kavitha, Trepat, Xavier, van Bezu, Jan, van Hinsbergh, Victor W. M., Carman, Christopher V., Brain, Joseph D., Fredberg, Jeffrey J., Butler, James P., van Nieuw Amerongen, Geerten P., (2011). Substrate stiffening promotes endothelial monolayer disruption through enhanced physical forces American Journal of Physiology - Cell Physiology , 300, (1), C146-C154

A hallmark of many, sometimes life-threatening, inflammatory diseases and disorders is vascular leakage. The extent and severity of vascular leakage is broadly mediated by the integrity of the endothelial cell (EC) monolayer, which is in turn governed by three major interactions: cell-cell and cell-substrate contacts, soluble mediators, and biomechanical forces. A potentially critical but essentially uninvestigated component mediating these interactions is the stiffness of the substrate to which the endothelial monolayer is adherent. Accordingly, we investigated the extent to which substrate stiffening influences endothelial monolayer disruption and the role of cell-cell and cell-substrate contacts, soluble mediators, and physical forces in that process. Traction force microscopy showed that forces between cell and cell and between cell and substrate were greater on stiffer substrates. On stiffer substrates, these forces were substantially enhanced by a hyperpermeability stimulus (thrombin, 1 U/ml), and gaps formed between cells. On softer substrates, by contrast, these forces were increased far less by thrombin, and gaps did not form between cells. This stiffness-dependent force enhancement was associated with increased Rho kinase activity, whereas inhibition of Rho kinase attenuated baseline forces and lessened thrombin-induced inter-EC gap formation. Our findings demonstrate a central role of physical forces in EC gap formation and highlight a novel physiological mechanism. Integrity of the endothelial monolayer is governed by its physical microenvironment, which in normal circumstances is compliant but during pathology becomes stiffer.

Keywords: Contraction, Human umbilical vein endothelial cells, Permeability, Traction force, Cell-cell contact, Cell-substrate contact, Substrate stiffness, Rho kinase, Vascular endothelial cadherin, Thrombin