Muscle Flashcards
What is nicotinic AChR?
A non-selective ligand gated cation channel permeable to sodium and potassium
Structure of nicotinic AChR?
5 subunits- 2a,B,delta and gamma, 2 binding sites between a+delta and a+gamma, 4 trans, extracellular N+C terminals
What are the alpha subunits on nicotinic AChR called?
CHRNA
What is the prevalence of Myasthenia Graves?
2-7 in 10000 in UK
What happens in Myasthenia Gravis?
Antibodies against AChR on post synaptic membrane- blocks receptor and also causes for it to be internalised so the numbers are reduced
What is the onset of Myasthenia Gravis?
Females early- 30s and males - late 60/70
What are the symptoms of Myasthenia Gravis?
Weakness and tiredness of skeletal muscle
What is the evidence that Myasthenia Graves is caused by antibodies?
87% of MG patients show positive- higher ABs for AChR. Injection of ABs into mice - show fewer ABs than normal and normal size
What are treatments for Myasthenia Graves?
Acetylcholinesterase inhbitors, Corticosteroids, other immunosuprressants, IV immunoglobulins, Plasmapheris, Thymectomy
Give an example of an Acetylcholinesterase and what they do to treat Myasthenia Gravis?
For mild Myasthenia Gravis, inhibits breakdown so enhances Aah e.g. Pyridostigme
What do corticosteroids to treat Myasthenia Graves and give an example?
Immunosuppressant for moderate/severe. Prednisolone
How are IV immunoglobulins used to treat Myasthenia Graves?
For severe, 400mg/kg for 5 days, mimics AChR so mops up ABs reducing levels
How is plasmapheresis used to treat Myasthenia Graves?
When life threatening, removal of ABs from plasma e.g. by filtration, immunoabsorption
How does thymectomy treat Myasthenia Graves?
For removal of AChR AB secreting B cells
What does Calcium bind to in SR?
Calrectuculin and calsequestrin
