sridevibandaru24
Forum Guru
Topics: 33
Posts: 434
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A pharmaceutical company has developed a drug that prevents egress of
Mg from the NMDA receptor. What is the most likely effect of this drug
ina patient with an acute stroke?
a. decrease risk for seizures due to hypomagnesemia
b. facilittion of Ca entry into the neuron and enhancement of
excitiotoxin mediated cell death
c. hyperpolarization of membrane and conduction block
d. preventation of Ca entry into the neuron and reducton of excitotoxin
mediated cell death
e. rapid depolarization of memebrane with lowering of the seizure
threshold.
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| drpkaur
Forum Guru
Topics: 196
Posts: 810
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d..?
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| fox
Forum Guru
Topics: 70
Posts: 727
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In experimental systems, magnesium antagonises many of these processes. Magnesium ions are antiexcitotoxic through inhibition of ischaemia-induced glutamate release,26 and through antagonist properties at the NMDA receptor ion channel,27–29 where magnesium ions provide a physiological voltage dependent block.30 Magnesium antagonises calcium entry via voltage gated channels of all types, enhances mitochondrial buffering of excessive calcium,31 and may prevent depletion of ATP.32 Intracellular magnesium concentrations in experimental systems are sufficiently high to antagonise a number of voltage gated ion channels including calcium, sodium and potassium,29 all implicated in cerebral ischaemia. Despite doubts about brain penetrance by systemically administered magnesium based on its pharmacokinetics, animal evidence that intravenous, intramuscular, oral, or intraperitoneal magnesium ameliorates direct excitotoxic brain injury induced by injection of NMDA,33 prevents NMDA induced seizures,34,35 increases free brain magnesium after head trauma,36 modifies NMDA receptor binding characteristics,37 and supports a potential neuronal mechanism of action in ischaemia.
I think, the correct answer should be D
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