Effect of concanavalin A on 5'-nucleotidase activity of rabbit blood platelets.

Nishio, Hiroaki; Takeshita, Keiko; Okugawa, Kimiko; Segawa, Tomio

doi:10.1254/jjp.43.230

Cited by 5 publications

(4 citation statements)

References 13 publications

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“…In our previous studies (8,9), we reported that c-AMP might regulate 5-HT transport and the inhibitory effect of Con A through the activation of protein kinase A activity. In mouse T lymphocytes, 'gated channels' for Ca", which could be opened directly by Con A binding to membrane glycoproteins, have been postulated, the operation of which may be regulated by cyclic nucleotides (18).…”

Section: Discussionmentioning

confidence: 95%

“…We have already shown that Con A selec tively inhibits 5-HT transport into platelets without the release reaction (7), and some transmembrane signaling system, including ecto-5'-nucleotidase (8) and/or adenylate cyclase (9) system, that operates via Con A binding has been suggested. In our present results, the inhibitory effect of Con A was antagonized by staurosporine and K-252a, highly active inhibitors of protein kinase C (10,11).…”

Section: Discussionmentioning

confidence: 99%

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Effect of Concanavalin A on Serotonin Transport into Blood Platelets: Possible Involvement of Protein Kinase C

Jikoh

Nishio

Okugawa

et al. 1990

Japanese Journal of Pharmacology

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Effect of Concanavalin A on Serotonin Transport into Blood Platelets: Possible Involvement of Protein Kinase C

Jikoh

Nishio

Okugawa

et al. 1990

Japanese Journal of Pharmacology

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“…The enzyme reaction was started by the addition of ATP or ADP to a final concentration of 0.5 mM. Platelet 5'-nucleotidase activity was assayed as described by Nishio et al (25). AMP hydrolysis was carried out in a medium containing 134 mM NaCl, 5.0 mM glucose, 1.5 mM MgCl 2 and 15 mM Tris-HCl buffer, pH 7.4.…”

Section: Determination Of Atp Diphosphohydrolase and 5'-nucleotidase mentioning

confidence: 99%

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

Frassetto

Schetinger

Schierholt

et al. 2000

Braz J Med Biol Res

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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. Correspondence

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“…In our previous studies, Con A was shown to have a potent inhibitory effect on 5-HT up take without the 5-HT release reaction (4), and suggested that some transmembrane sig naling system, including ecto-5'-nucleotidase (5) and/or the adenylate cyclase (6) system, might be involved in the effect of Con A. Adenosine, a product of ecto-5'-nucleotidase and endogenous inhibitor of adenylate cyclase activity, has been suggested to act as the mod ulator in these transmembrane signaling sys tems (5,6).…”

mentioning

confidence: 97%

Effect of Concanavalin A on Intracellular Calcium Concentration in Single Blood Platelets

Ikegami

Nishio

Fukuda

et al. 1991

Japanese Journal of Pharmacology

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ABSTRACT-Mobilization of Ca++ was estimated in single rabbit blood platelets with digital imaging microscopy. Concanavalin A (Con A) caused a rapid initial in crease in intracellular concentration of Ca++ ([Ca++];) with a latent time of about 20 sec, followed by a sustained increase in [Ca++];. This effect of Con A was antago nized by a-methyl-D-mannose, which already was shown to antagonize the inhibitory effect of Con A on 5-HT transport, indicating that this effect of Con A was also de rived from its binding to cell surface glycoproteins. The presence of EGTA in the medium did not affect the initial rise, but inhibited the latter phase of sustained rise. Thus, Con A induced elevation of [Ca++]; was suggested to consist of two different processes: mobilization of Ca+ + from the intracellular storage sites and successive Ca + + influx through Ca + + channels. The effect of Con A on the 5-HT transport was tested in the presence of EGTA, a condition where no Ca+ + influx occurs. The re sults indicate that Con A induced inhibition of 5-HT transport was not influenced by EGTA in the medium. It is suggested that the effect of Con A on 5-HT transport might be exerted through the Ca ++ mobilization from its intracellular storage sites.

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Effect of concanavalin A on 5'-nucleotidase activity of rabbit blood platelets.

Abstract: Abstract-Ecto-5'-nucleotidase

Cited by 5 publications

References 13 publications

Effect of Concanavalin A on Serotonin Transport into Blood Platelets: Possible Involvement of Protein Kinase C

Effect of Concanavalin A on Serotonin Transport into Blood Platelets: Possible Involvement of Protein Kinase C

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

Effect of Concanavalin A on Intracellular Calcium Concentration in Single Blood Platelets

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