Efeito da despolarizaÃÃo da membrana plasmÃtica na modulaÃÃo da apoptose de neutrÃfilos mediada por lipopolissacarÃdeo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Among its many biologic activities, extracellular calcium plays a key role in the maintenance of plasma membrane polarization. The effect of membrane depolarization induced by low extracellular calcium concentration or ouabain in neutrophil (PMN) apoptosis and Caspase-3 expression are evaluated. PMN were isolated from blood of healthy lab volunteers by density gradient centrifugation, and cultured for 18h in normal (1.8mM) or low (>10nM) calcium medium or with the Na+K+-ATPase inhibitor, ouabain (1mM). Apoptosis was quantified with flow cytometer by the nuclear uptake of propidium iodide. Caspase-3 protein was evaluated by Western blot. There were no observed effects in PMN apoptosis cultured only with depolarizing stimuli. The inhibitory effects of LPS (1ug/ml) on PMN apoptosis were abolished by culture of PMN in low Ca++ medium, and restored by the addition of divalent cations (calcium, strontium or manganese); ouabain similarly blocked the inhibitory effects of LPS. Both calcium depletion and ouabain reduced expression of Pro-Caspase-3. Extracellular calcium depletion or ouabain, two distinct stimuli that induce plasma membrane depolarization, block the LPS-mediated inhibition of PMN apoptosis, and alter expression and activation of caspases. These observations may establish a novel mechanism regulating PMN survival

ASSUNTO(S)

cirurgia plasmatic membrane depolarization lipopolysaccharide despolarizaÃÃo da membrana plasmÃtica apoptose lipopolissacarÃdeo apoptosis neutrophils neutrÃfilos

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