Escherichia coli lipopolysaccharide impairs the calcium signaling pathway in mesangial cells: role of angiotensin II receptors
Data
2010-06-01
Autores
Maquigussa, Edgar 
Arnoni, Carine P.
Cristovam, Priscila C.
Oliveira, Andrea S. de
Higa, Elisa M. S.
Mostrar mais
Tipo
Artigo
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Sepsis causes impaired vascular reactivity, hypotension and acute renal failure. the ability of the Escherichia coli endotoxin (lipopolysaccharide [LPS]) to impair agonist-induced contractility in mesangial cells, which contributes to LPS-induced renal dysfunction, was evaluated. Agonist-induced intracellular calcium ([Ca(2+)]i) mobilization was analyzed using angiotensin II (AngII). the effect of LPS on the levels of the renin-angiotensin system (RAS) components and the roles of vasodilatation-inducing molecules including AT2 receptor (AT2R) and nitric oxide (NO) in the cell reactivity were also evaluated. Confluent human mesangial cells (HMCs) were stimulated with LPS (0111-B4, 100 mu g/mL). AngII-induced [Ca(2+)]i mobilization was measured by fluorometric analysis using Fura-2AM in the absence and presence of an AT2R antagonist (PD123319). the mRNA and protein levels for angiotensinogen, renin, angiotensin-converting enzyme, AT1R and AT2R were analyzed by realtime reverse transcriptase-polymerase chain reaction and Western blot, respectively. NO production was measured by the chemiluminescence method in the culture media after 24, 48 and 72 h of LPS incubation. After 24 h, LPS-stimulated HMCs displayed lower basal [Ca(2+)]i and an impaired response to AngII-induced rise in [Ca(2+)]i. LPS significantly increased AT2R levels, but did not cause significant alterations of RAS components. PD123319 restored both basal and AngII-induced [Ca(2+)]i peak, suggesting an involvement of AT2R in these responses. the expected increase in NO production was significant only after 72 h of LPS incubation and it was unaffected by PD123319. Results showed that LPS reduced the reactivity of HMCs to AngII and suggest that the vasodilatation induced by AT2R is a potential mediator of this response through a pathway independent of NO.
Descrição
Citação
Experimental Biology and Medicine. Maywood: Soc Experimental Biology Medicine, v. 235, n. 6, p. 761-767, 2010.