Transport and metabolism of adenosine in the perfused human placenta

Acevedo, C.G.; Rojas, Susana; Ramírez, Myriam; Bravo, Iván

doi:10.1016/0143-4004(95)90030-6

Cited by 20 publications

(20 citation statements)

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“…Preparation of standards and counting procedures have been previously described (Acevedo et al 1995). Tissue uptake of ¬_ [ÅH]arginine (U) in sequential effluent samples was estimated according to Yudilevich (1985) The Michaelis-Menten equation for two saturable components was fitted to uptake data using the computer programs Enzfitter and Ultra Fit (Elsevier, Biosoft).…”

Section: ¬_[åh]arginine (0·33 ìò) (Control); ¬_[åh]arginine (0·33 ìò)mentioning

confidence: 99%

“…Since previous information on cationic amino acid transport systems of human placenta has only been obtained using isolated membrane vesicle preparations, we decided to investigate cationic amino acid transporters expressed at the fetal side of human placenta in an established model of isolated perfused cotyledon (Penfold et al 1981;Acevedo et al 1995). Another aim of this study was to investigate whether low-dose aspirin used for the prevention of PE affects ¬_arginine transport in the human placenta.…”

mentioning

confidence: 99%

“…The technique of perfusion of the placental cotyledon was that of Penfold et al (1981), which was modified by perfusing only the fetal vascular compartment instead of the dual perfusion model (Acevedo et al 1995). As soon as possible after delivery (within 15 min), a suitable fetal vein and artery pair on the surface of the chorionic plate, leading to a peripheral cotyledon, were cannulated with plastic tubing.…”

mentioning

confidence: 99%

“…The perfusion pressure was continuously monitored with a Statham P23D transducer and a Grass chart recorder. Preparation viability was assessed by measuring lactic dehydrogenase activity in the perfusate of the isolated perfused cotyledon as described by Penfold et al (1981) and Acevedo et al (1995). In addition, we measured POµ in both arterial and venous effluents (Ram úrez et al 1997).…”

mentioning

confidence: 99%

“…After a stabilization period, in which the cotyledon was perfused with the Ringer-Krebs solution for at least 30 min, cellular uptake of ¬_[ÅH]arginine was measured in relation to an extracellular tracer ([ 14 C]sucrose) using a rapid, single-circulation paired-tracer technique, as already described (Acevedo et al 1995;Ram úrez et al 1997). A 200 ìl bolus containing a mixture of ¬_ [ÅH]arginine (4 ìCi; 0·1 ìÒ) and [ 14 C]sucrose (1 ìCi) was intra-arterially injected and was followed by the immediate sequential collection of six samples from the venous perfusate at 1 min intervals.…”

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confidence: 99%

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L-Arginine Transport at the Fetal Side of Human Placenta: Effect of Aspirin in Pregnancy

ACEVEDO¹,

ROJAS²,

BRAVO³

1999

Exp. Physiol.

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summary ¬_Arginine transport by the fetal side of human placenta was investigated through the characterization of ¬_ [ÅH]arginine uptake in isolated perfused cotyledon. Competitive inhibition experiments suggest the presence of at least two transport systems: a Na¤-independent, pHinsensitive system inhibitable by cationic amino acids, similar to system y¤, and a Na¤-dependent system which recognizes both cationic and neutral amino acids only in the presence of Na¤, i.e. a B°, + -like system. The kinetic analysis of ¬-arginine uptake in the presence of Na¤ revealed that the process is mediated by saturable components: a high-affinity system (Km = 167 ± 18·0 ìÒ; Vmax = 0·174 ± 0·012 ìmol min¢) and a low-affinity carrier (Km = 980 ± 112 ìÒ; Vmax = 1·60 ± 0·12 ìmol min¢). In the absence of Na¤, ¬_arginine uptake was fitted by one model with a Michaelis-Menten constant of 200 ± 24·8 ìÒ. These results suggest that the high-affinity component corresponds to the Na¤-independent system y¤, whilst the low-affinity system may represent the activity of the Na¤-dependent B°, + transporter. Kinetic studies in placentae taken from aspirin-treated pregnancies showed that ¬_arginine is transported with a significantly higher affinity (Km = 42·5 ± 5·7 ìÒ), but with a lower capacity (Vmax = 0·064 ± 0·003 ìmol min¢) than in the non-treated group. The latter finding suggests that aspirin would facilitate the uptake of the NO precursor only at very low arginine concentrations.

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Section: ¬_[åh]arginine (0·33 ìò) (Control); ¬_[åh]arginine (0·33 ìò)mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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L-Arginine Transport at the Fetal Side of Human Placenta: Effect of Aspirin in Pregnancy

ACEVEDO¹,

ROJAS²,

BRAVO³

1999

Exp. Physiol.

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Effect of chronic gestational treatment with the adenosine A₁ receptor agonist R‐phenylisopropyladenosine on metabotropic glutamate receptors/phospholipase C pathway in maternal and fetal brain

León¹,

Albasanz²,

Castillo³

et al. 2008

J of Neuroscience Research

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Pregnant Wistar rats were orally treated with the adenosine receptor agonist R-phenylisopropyladenosine (R-PIA) throughout the gestational period, and the status of the metabotropic glutamate (mGlu) receptor/phospholipase C transduction pathway from maternal and fetal brain was analyzed. In mothers' brains, radioligand binding assays revealed a significant decrease in the Bmax value, without any significant alteration in Kd value. Similar results were observed in the steady-state level of mGlu(1) and mGlu(5) receptors assayed by Western blot, suggesting that both receptor subtypes were modulated by chronic R-PIA treatment. mRNA coding mGlu(1) or mGlu(5) receptors was not altered, suggesting a posttranscriptional modulation as a possible mechanism of the loss of mGlu(1) and mGlu(5) receptors at the membrane surface. Moreover, phospholipase C stimulated by (R,S)-3,5-dihydroxyphenylglycine (DHPG), a selective agonist of group I mGlu receptors, was also significantly decreased after R-PIA treatment, suggesting a heterologous desensitization of group I mGlu/PLC pathway in maternal brain. Western blot and RT-PCR assays showed that neither alphaG(q/11) nor PLCbeta(1) was affected by R-PIA treatment. In fetal brain, no significant differences in mGlu receptors/PLC transduction pathway were observed after R-PIA treatment. These results suggest that chronic R-PIA intake during pregnancy modulates group I mGlu receptor signalling pathway in maternal brain, promoting a down-regulation of mGlu(1) and mGlu(5) receptors and a heterologous desensitization of the mGlu/PLC system.

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Purinergic signalling in the reproductive system in health and disease

Burnstock

2013

Purinergic Signalling

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There are multiple roles for purinergic signalling in both male and female reproductive organs. ATP, released as a cotransmitter with noradrenaline from sympathetic nerves, contracts smooth muscle via P2X1 receptors in vas deferens, seminal vesicles, prostate and uterus, as well as in blood vessels. Male infertility occurs in P2X1 receptor knockout mice. Both short-and long-term trophic purinergic signalling occurs in reproductive organs. Purinergic signalling is involved in hormone secretion, penile erection, sperm motility and capacitation, and mucous production. Changes in purinoceptor expression occur in pathophysiological conditions, including pre-eclampsia, cancer and pain.

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Transport and metabolism of adenosine in the perfused human placenta

Cited by 20 publications

References 27 publications

L-Arginine Transport at the Fetal Side of Human Placenta: Effect of Aspirin in Pregnancy

L-Arginine Transport at the Fetal Side of Human Placenta: Effect of Aspirin in Pregnancy

Effect of chronic gestational treatment with the adenosine A₁ receptor agonist R‐phenylisopropyladenosine on metabotropic glutamate receptors/phospholipase C pathway in maternal and fetal brain

Purinergic signalling in the reproductive system in health and disease

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Transport and metabolism of adenosine in the perfused human placenta

Cited by 20 publications

References 27 publications

L-Arginine Transport at the Fetal Side of Human Placenta: Effect of Aspirin in Pregnancy

L-Arginine Transport at the Fetal Side of Human Placenta: Effect of Aspirin in Pregnancy

Effect of chronic gestational treatment with the adenosine A1 receptor agonist R‐phenylisopropyladenosine on metabotropic glutamate receptors/phospholipase C pathway in maternal and fetal brain

Purinergic signalling in the reproductive system in health and disease

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Effect of chronic gestational treatment with the adenosine A₁ receptor agonist R‐phenylisopropyladenosine on metabotropic glutamate receptors/phospholipase C pathway in maternal and fetal brain