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Brain ischemia alters platelet ATP disphosphohydrolase and 5'-nucleotidase activities in naive and preconditioned rats

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Brain ischemia alters platelet ATP disphosphohydrolase and 5'-nucleotidase activities in naive and preconditioned rats

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Título Brain ischemia alters platelet ATP disphosphohydrolase and 5'-nucleotidase activities in naive and preconditioned rats
Autor Frasseto, Silvana Soriano
Schetinger, Maria Rosa Chitolina
Schierholt, Rejane Cristina
Webber, Analupe
Bonan, Carla Denise
Wyse, Angela Terezinha de Souza
Dias, Renato Dutra
Netto, Carlos Alexandre
Sarkis, João José Freitas
Abstract The effects of transient forebrain ischemia, reperfusion and ischemic preconditioning on rat blood platelet ATP diphosphohydrolase and 5'- nucleotidase activities were evaluated. Adult Wistar rats were submitted to 2 or 10 min of single ischemic episodes, or to 10 min of ischemia 1 day after a 2-min ischemic episode (ischemic preconditioning) by the four-vessel occlusion method. Rats submitted to single ischemic insults were reperfused for 60 min and for 1, 2, 5, 10 and 30 days after ischemia; preconditioned rats were reperfused for 60 min 1 and 2 days after the long ischemic episode. Brain ischemia (2 or 10 min) inhibited ATP and ADP hydrolysis by platelet ATP diphosphohydrolase. On the other hand, AMP hydrolysis by 5'-nucleotidase was increased after 2, but not 10, min of ischemia. Ischemic preconditioning followed by 10 min of ischemia caused activation of both enzymes. Variable periods of reperfusion distinctly affected each experimental group. Enzyme activities returned to control levels in the 2-min group. However, the decrease in ATP diphosphohydrolase activity was maintained up to 30 days of reperfusion after 10-min ischemia. 5'-Nucleotidase activity was decreased 60 min and 1 day following 10-min ischemia; interestingly, enzymatic activity was increased after 2 and 5 days of reperfusion, and returned to control levels after 10 days. Ischemic preconditioning cancelled the effects of 10-min ischemia on the enzymatic activities. These results indicate that brain ischemia and ischemic preconditioning induce peripheral effects on ecto-enzymes from rat platelets involved in nucleotide metabolism. Thus, ATP, ADP and AMP degradation and probably the generation of adenosine in the circulation may be altered, leading to regulation of microthrombus formation since ADP aggregates platelets and adenosine is an inhibitor of platelet aggregation.
Contido em Brazilian journal of medical and biological research = Revista brasileira de pesquisas médicas e biológicas. Ribeirão Preto, SP. Vol. 33, no. 11 (Nov 2000), p. 1369-1377
Assunto Bioquímica
[en] 5'-Nucleotidase
[en] ATP diphosphohydrolase
[en] Brain ischemia
[en] Ischemic preconditioning
[en] Rat platelets
Origem Nacional
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/21169
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