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Ectonucleotidase activities in Sertoli cells from immature rats

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Ectonucleotidase activities in Sertoli cells from immature rats

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Título Ectonucleotidase activities in Sertoli cells from immature rats
Autor Casali, Emerson Andre
Silva, Tiago Rodrigues da
Gelain, Daniel Pens
Kaiser, Glória Regina Rodrigues de Freitas
Battastini, Ana Maria Oliveira
Sarkis, João José Freitas
Bernard, Elena Aida
Abstract Sertoli cells have been shown to be targets for extracellular purines such as ATP and adenosine. These purines evoke responses in Sertoli cells through two subtypes of purinoreceptors, P2Y2 and PA1. The signals to purinoreceptors are usually terminated by the action of ectonucleotidases. To demonstrate these enzymatic activities, we cultured rat Sertoli cells for four days and then used them for different assays. ATP, ADP and AMP hydrolysis was estimated by measuring the Pi released using a colorimetric method. Adenosine deaminase activity (EC 3.5.4.4) was determined by HPLC. The cells were not disrupted after 40 min of incubation and the enzymatic activities were considered to be ectocellularly localized. ATP and ADP hydrolysis was markedly increased by the addition of divalent cations to the reaction medium. A competition plot demonstrated that only one enzymatic site is responsible for the hydrolysis of ATP and ADP. This result indicates that the enzyme that acts on the degradation of tri- and diphosphate nucleosides on the surface of Sertoli cells is a true ATP diphosphohydrolase (EC 3.6.1.5) (specific activities of 113 ± 6 and 21 ± 2 nmol Pi mg-1 min-1 for ATP and ADP, respectively). The ecto-5'- nucleotidase (EC 3.1.3.5) and ectoadenosine deaminase activities (specific activities of 32 ± 2 nmol Pi mg-1 min-1 for AMP and 1.52 ± 0.13 nmol adenosine mg-1 min-1, respectively) were shown to be able to terminate the effects of purines and may be relevant for the physiological control of extracellular levels of nucleotides and nucleosides inside the seminiferous tubules.
Contido em Brazilian journal of medical and biological research = Revista brasileira de pesquisas médicas e biológicas. Ribeirão Preto, SP. Vol. 34, no. 10 (Oct. 2001), p. 1247-1256
Assunto Bioquímica
[en] ATP diphosphohydrolase
[en] Ecto-5’-nucleotidase
[en] Ectoadenosine deaminase
[en] Purine nucleotides
[en] Sertoli cells
Origem Nacional
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/21140
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