Nucleoside transporter-mediated uptake and release of [3H]l-adenosine in DDT1 MF-2 smooth muscle cells

Foga, Irene O.; Geiger, Jonathan D.; Parkinson, Fiona E.

doi:10.1016/s0014-2999(96)00720-0

Cited by 5 publications

(3 citation statements)

References 18 publications

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“…More interesting is the fact that 5‐ITU also blocks adenosine transport at a similar IC 50. This is of therapeutic interest as it would allow 5‐ITU to trap adenosine inside the cell and thereby enable adenosine receptor–independent epigenetic activity previously demonstrated to play a key role in epilepsy prevention. Unfortunately, it is currently not practical to experimentally determine the concentrations of the extracellular vs intracellular adenosine pools.…”

Section: Discussionmentioning

confidence: 99%

Transient use of a systemic adenosine kinase inhibitor attenuates epilepsy development in mice

Sandau

Yahya²,

Bigej³

et al. 2019

Epilepsia

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Summary Objective Over one‐third of all patients with epilepsy are refractory to treatment and there is an urgent need to develop new drugs that can prevent the development and progression of epilepsy. Epileptogenesis is characterized by distinct histopathologic and biochemical changes, which include astrogliosis and increased expression of the adenosine‐metabolizing enzyme adenosine kinase (ADK; EC 2.7.1.20). Increased expression of ADK contributes to epileptogenesis and is therefore a target for therapeutic intervention. We tested the prediction that the transient use of an ADK inhibitor administered during the latent phase of epileptogenesis can mitigate the development of epilepsy. Methods We used the intrahippocampal kainic acid (KA) mouse model of temporal lobe epilepsy, which is characterized by ipsilateral hippocampal sclerosis with granule cell dispersion and the development of recurrent hippocampal paroxysmal discharges (HPDs). KA‐injected mice were treated with the ADK inhibitor 5‐iodotubercidin (5‐ITU, 1.6 mg/kg, b.i.d., i.p.) during the latent phase of epileptogenesis from day 3‐8 after injury; the period when gradual increases in hippocampal ADK expression begin to manifest. HPDs were assessed at 6 and 9 weeks after KA administration followed by epilepsy histopathology including assessment of granule cell dispersion, astrogliosis, and ADK expression. Results 5‐ITU significantly reduced the percent time in seizures by at least 80% in 56% of mice at 6 weeks post‐KA. This reduction in seizure activity was maintained in 40% of 5‐ITU–treated mice at 9 weeks. 5‐ITU also suppressed granule cell dispersion and prevented maladaptive ADK increases in these protected mice. Significance Our results show that the transient use of a small‐molecule ADK inhibitor, given during the early stages of epileptogenesis, has antiepileptogenic disease‐modifying properties, which provides the rationale for further investigation into the development of a novel class of antiepileptogenic ADK inhibitors with increased efficacy for epilepsy prevention.

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Section: Discussionmentioning

confidence: 99%

Transient use of a systemic adenosine kinase inhibitor attenuates epilepsy development in mice

Sandau

Yahya²,

Bigej³

et al. 2019

Epilepsia

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“…Therefore, release could be occurring via an inhibitor-insensitive equilibrative transporter or one or more of the inhibitor-insensitive concentrative transporters, either because intracellular adenosine concentration had built up in excess of what the transport system could maintain or because the sodium gradient had diminished, for example because of a compromise in energy metabolism by nitric oxide (Thorn and Jarvis, 1996). In fact, iodoacetate-evoked release of adenosine by a concentrative transporter has been observed (Foga et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Nitric Oxide-Stimulated Increase in Extracellular Adenosine Accumulation in Rat Forebrain Neurons in Culture Is Associated with ATP Hydrolysis and Inhibition of Adenosine Kinase Activity

Rosenberg

et al. 2000

J. Neurosci.

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Adenosine is a putative endogenous sleep-inducing substance, and nitric oxide has been implicated in arousal and sleep mechanisms. We found that various nitric oxide donors, including diethylamine NONOate (DEA/NO), stimulated large increases in extracellular adenosine in nearly pure cultures of forebrain neurons. The effect of DEA/NO could be blocked by 2-phenyl-4,4,5, 5-tetramethyl-imidazoline-1-oxyl-oxide and could not be mimicked by degraded solutions of DEA/NO or by DEA itself; therefore, it was caused by nitric oxide release on hydrolysis of the parent compound. The accumulation of adenosine was not blocked by probenecid or GMP, suggesting that neither extracellular cAMP nor extracellular AMP was the source, and that adenosine was therefore the most likely species transported across the plasma membrane. To pursue this further, we tested the effect of DEA/NO on cellular ATP and found a significant fall in ATP associated with exposure to nitric oxide. In addition, exposure to DEA/NO nearly completely inhibited adenosine kinase activity. It has been found previously that adenosine kinase is inhibited by its substrate, adenosine. We found that exposure to nitric oxide increased intracellular adenosine to 125 +/- 18% of control values (p < 0.01), consistent with the possibility that in our system the inhibition of adenosine kinase is related to an increase in intracellular adenosine, and that the effect of nitric oxide on extracellular adenosine is significantly potentiated by substrate inhibition of adenosine kinase. Furthermore, nitric oxide-stimulated adenosine accumulation may be important in the regulation of behavioral state.

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“…Extracellular levels of adenosine are regulated by an efficient uptake and metabolism in erythrocytes and endothelial cells, the latter having a particularly high density of es nucleoside transporters (1.2 × 10 6 transporters cell −1 ; see Sobrevia et al 1994). Adenosine transport is mediated by a similar high affinity transport system in smooth muscle cells (Pearson et al 1978; Beck et al 1983; Foga et al 1996; Borgland & Parkinson, 1998). We have recently characterized adenosine transport in human smooth muscle cells cultured from explants obtained from umbilical artery from normal or gestational diabetic pregnancies (Aguayo & Sobrevia, 2000).…”

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confidence: 99%

Modulation of adenosine transport by insulin in human umbilical artery smooth muscle cells from normal or gestational diabetic pregnancies

Aguayo

Flores

Parodí

et al. 2001

The Journal of Physiology

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Adenosine transport was measured in human cultured umbilical artery smooth muscle cells, isolated from non‐diabetic or gestational diabetic pregnancies, under basal conditions and after pretreatment in vitro with insulin. Adenosine transport in non‐diabetic smooth muscle cells was significantly increased by insulin (half‐maximal stimulation at 0.33 ± 0.02 nm, 8 h) and characterized by a higher maximal rate (Vmax) for nitrobenzylthioinosine (NBMPR)‐sensitive (es) saturable nucleoside transport (17 ± 5 vs. 52 ± 12 pmol (μg protein)−1 min−1, control vs. insulin, respectively) and maximal binding sites (Bmax) for [3H]NBMPR (0.66 ± 0.07 vs. 1.1 ± 0.1 fmol (μg protein)−1, control vs. insulin, respectively), with no significant changes in Michaelis‐Menten (Km) and dissociation (Kd) constants. In contrast, in smooth muscle cells from diabetic pregnancies, where the values of Vmax for adenosine transport (59 ± 4 pmol (μg protein)−1 min−1) and Bmax for [3H]NBMPR binding (1.62 ± 0.16 fmol (μg protein)−1) were significantly elevated by comparison with non‐diabetic cells, insulin treatment (1 nm, 8 h) reduced the Vmax for adenosine transport and Bmax for [3H]NBMPR binding to levels detected in non‐diabetic cells. In non‐diabetic cells, the stimulatory effect of insulin on adenosine transport was mimicked by dibutyryl cGMP (100 nm) and reduced by inhibitors of phosphatidylinositol 3‐kinase (10 nm wortmannin), nitric oxide synthase (100 μmNG‐nitro‐l‐arginine methyl ester, l‐NAME) or protein synthesis (1 μm cycloheximide), whereas inhibition of adenylyl cyclase (100 μm SQ‐22536) had no effect. Wortmannin or SQ‐22536, but not l‐NAME or cycloheximide, attenuated the inhibitory action of insulin on the diabetes‐induced stimulation of adenosine transport. Protein levels of inducible NO synthase (iNOS) were similar in non‐diabetic and diabetic cells, but were increased by insulin (1 nm, 8 h) only in non‐diabetic smooth muscle cells. Our results suggest that adenosine transport via the es nucleoside transporter is modulated differentially by insulin in either cell type. Insulin increased adenosine transport in non‐diabetic cells via NO and cGMP, but inhibited the diabetes‐elevated adenosine transport via activation of adenylyl cyclase, suggesting that the biological actions of adenosine may be altered under conditions of sustained hyperglycaemia in uncontrolled diabetes.

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Nucleoside transporter-mediated uptake and release of [3H]l-adenosine in DDT1 MF-2 smooth muscle cells

Cited by 5 publications

References 18 publications

Transient use of a systemic adenosine kinase inhibitor attenuates epilepsy development in mice

Transient use of a systemic adenosine kinase inhibitor attenuates epilepsy development in mice

Nitric Oxide-Stimulated Increase in Extracellular Adenosine Accumulation in Rat Forebrain Neurons in Culture Is Associated with ATP Hydrolysis and Inhibition of Adenosine Kinase Activity

Modulation of adenosine transport by insulin in human umbilical artery smooth muscle cells from normal or gestational diabetic pregnancies

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