DrVirgo
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47. A pharmaceutical company has developed a drug that prevents egress of Mg2+ from the N-methyl-D-aspartate (NMDA) receptor. What is the most likely effect of this drug in a patient with an acute stroke?
A) Decreased risk for seizures due to hypomagnesemia
B) Facilitation of Ca2+ entry into the neuron and enhancement of excitotoxin-mediated cell death
C) Hyperpolarization of membrane and conduction block
D) Prevention of Ca2+ entry into the neuron and reduction of excitotoxin-mediated cell death
E) Rapid depolarization of membrane with lowering of the seizure threshold
Is it D???
Can anyone give an explanation about NMDA receptors drugs associated with them?  Thanks.
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| krsna
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i think its c.
the magnesium ion sits in the channel of the nmda receptor.when the ligand binds the mg ion moves out allowing influx of na, ca etc...so if we block mg egress there is no depolarisation and a conductiion block develops
hopes this helps.
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| krsna
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i think its c.
magnesium ion sits in the channel of the nmda receptor.when the ligand binds the mg ion moves out allowing influx of na, ca etc...so if we block mg egress there is no depolarisation and a conductiion block develops
hope this helps.
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| drpkaur
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ca entry into cells leads to cell death. If mg which is also a bivalent ion is sitting on the nmda receptor with greater affinity, it will prevent the ca influx which would cause irreversible cell death....just my thought ..i think it's D....
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| DrVirgo
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I go with D!
.
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| rman
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Vote for D as well; it's true and it answers the question best (i.e. has something to do with stroke)
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| disha
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is NMDA RECEPTOR FOR GLUTAMIC ACID?
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| Cedrick
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C
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| funnyhat
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D- so Glutamate first binds to the AMPA channel and partially depolarizes the cell, this knocks the Mg off the NMDA rec. leaving it open to bind Glutamate and further depolarize the cell --> a response. So if you can't knock of Mg then glutamate can't bine ..no response. Hope that helps
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| robin082006
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D, this has been discussed.
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| Cedrick
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yes it does
D
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| Musuq
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The NMDA receptor (NMDAR) is an ionotropic receptor for glutamate (NMDA (N-methyl d-aspartate) is a name of its selective specific agonist). Activation of NMDA receptors results in the opening of an ion channel which is nonselective to cations. This allows flow of Na+ and K+ ions, and small amounts of Ca2+ . Calcium flux through NMDARs is thought to play a critical role in synaptic plasticity, a cellular mechanism for learning and memory. The NMDA receptor is interesting in that is both ligand-gated but also voltage-dependent.
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| Allison
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I do not understand this question, could someone please try to explain it again.
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| NE
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NMDA rec. opening is blocked by magnesium ion (Mg2+). An Mg2+ ion is removed only when the electrical charge inside the cell rises to a specific value and when Mg is removed the Ca enters in cell.If you can block the Mg you prevent the increases ic Ca.
Maybe the pictures can help!
Attached Files:
NMDA.jpg (141 KB, 41 downloads)
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| NE
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Attached Files:
ca in cell.gif (36 KB, 41 downloads)
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| linaorvos
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good pic
D then....
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