USMLE Myasthenia Gravis, Pyridostigmine and Hypertention

[Erlomd]

I recently came across a fairly easy question on myasthenia gravis where one of the known treatments is pyridostigmine (an anti cholinesterase).
wouldn't acetylcholine cause vasodilation increasing nitric oxide in blood vessels? So, is it right to say that myasthenia gravis patients are more prone to acquire hypertension since they make antibodies against acetylcholine receptors?

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[Handinhand]

No. Myasthenia Gravis are antibodies against the nicotinic ACH receptor.

 

[Erlomd]

I see, so since nicotinic receptors allow ions to pass through them causing an effect...then if they are blocked or not present then a receptor who uses an ion will not exert an effect...so in that case nicotinic receptors in MG will not express an effect of any sort. hence hyper or hypotension will not have any significance on MG by those means...thanks

 

[GadRads]

I recently came across a fairly easy question on myasthenia gravis where one of the known treatments is pyridostigmine (an anti cholinesterase).
wouldn't acetylcholine cause vasodilation increasing nitric oxide in blood vessels? So, is it right to say that myasthenia gravis patients are more prone to acquire hypertension since they make antibodies against acetylcholine receptors?

The muscarinic receptors in blood vessels aren't innervated. That is, there are no cholinergic post-synaptics supplying those receptors. So cholinesterase inhibitors won't cause hypotension. The way to cause hypotension by cholinergic action is to directly administer ACh to the blood vessel. It is similar to beta-2 receptors in the vasculature. Norepinephrine will never find beta-2 receptors in blood vessels since these receptors aren't innervated, but instead these beta-2 receptors get stimulated by epinephrine (and some minor NE) secreted into the blood stream by the adrenal medulla.

Don't confuse muscarinic with nicotinic ACh receptors. Nicotinic Ach receptors have nothing to do with vasodilation.