Submitted on November 23, 2005
Accepted on June 6, 2006
Norepinephrine Induces Calcium Spikes And Proinflammatory Actions In Human Hepatic Stellate Cells
Pau Sancho-Bru1, Ramon Bataller2*, Jordi Colmenero2, Xavier Gasull3, Montserrat Moreno2, Vicente Arroyo2, David A Brenner4, and Pere Gines2
1 Liver Unit, Institut Clinic de Malalties Digestives i Metaboliques, Hospital Clinic, Institut Investigacions Biomediques August Pi i Sunyer (IDIBAPS),, Barcelona, Catalonia, Spain
2 Liver Unit, Institut Clinic de Malalties Digestives i Metaboliques, Hospital Clinic, Institut Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain
3 Laboratory of Neurophysiology, University of Barcelona School of Medicine, Institut Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain
4 Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, United States
* To whom correspondence should be addressed. E-mail: bataller{at}clinic.ub.es.
Background and aims: Catecholamines participate in the pathogenesis of portal hypertension and liver fibrosis through 
1 adrenoceptors. However, the underlying cellular and molecular mechanisms are largely unknown. Here, we investigate the effects of norepinephrine (NE) on human hepatic stellate cells (HSC), which exert vasoactive, inflammatory and fibrogenic actions in the injured liver.
Methods: Adrenoceptor expression was assessed in human HSC by RT-PCR and immunocytochemistry. Intracellular calcium concentration ([Ca2+]i) was studied in fura-2 loaded cells. Cell contraction was studied by assessing wrinkle formation and myosin light chain II (MLC-II) phosphorylation. Cell proliferation and collagen-1(I) expression were assessed by 3H-thymidine incorporation and quantitative PCR, respectively. NF
B activation was assessed by luciferase reporter gene and p65 nuclear translocation. Chemokine secretion was assessed by ELISA.
Results: Normal human livers expressed 1A adrenoceptors, which were markedly up-regulated in livers with advanced fibrosis. Activated human HSC expressed 1A adrenoceptors. Norepinephrine induced multiple rapid [Ca2+]ioscillations (Ca2+ spikes). Prazosin (1 blocker) completely prevented NE-induced Ca2+ spikes, while propranolol (nonspecific 
blocker) partially attenuated this effect. Norepinephrine caused phosphorylation of MLC-II, and cell contraction. In constrast, NE did not affect cell proliferation nor collagen 1(I) expression. Importantly, NE stimulated the secretion of inflammatory chemokines (RANTES and interleukin-8) in a dose-dependent manner. Prazosin blocked NE-induced chemokine secretion. Norepinephrine stimulated NFB activation. BAY11-7082, a specific NFB inhibitor, blocked NE-induced chemokine secretion.
Conclusions: NE stimulates NFB and induces cell contraction and proinflammatory effects in human HSC. Catecholamines may participate in the pathogenesis of portal hypertension and liver fibrosis by targeting HSC.
