Q. connection of tyramine and catecholamine? - USMLE Forums
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Old 08-22-2015
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Default Q. connection of tyramine and catecholamine?

Q. FA (autonomic drugs) says " phentolamine is given to patients on MAO inhibitors who eat tyramine-containing foods".I know it's because MAOI & tyramine both increases catecholamine causing hyertensive crisis and Phentolamine as a vasodialtor can be a good choice in this case. My question is- what is the exact connection of tyramine and catecholamine? I know it is tyrosine which is the precursor of catecholamines but NOT tyramine (I too know tyramine is derived from tyrosine)?Then, how tyramine contributes in increased catecholamines?Any biochemistry or pathophysiology which explains the relationship of tyramine and catecholamines OR increased tyramine leading to increased catecholamine?Thanks.
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Old 08-22-2015
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Quote:
Originally Posted by Aumsai View Post
Q. FA (autonomic drugs) says " phentolamine is given to patients on MAO inhibitors who eat tyramine-containing foods".I know it's because MAOI & tyramine both increases catecholamine causing hyertensive crisis and Phentolamine as a vasodialtor can be a good choice in this case. My question is- what is the exact connection of tyramine and catecholamine? I know it is tyrosine which is the precursor of catecholamines but NOT tyramine (I too know tyramine is derived from tyrosine)?Then, how tyramine contributes in increased catecholamines?Any biochemistry or pathophysiology which explains the relationship of tyramine and catecholamines OR increased tyramine leading to increased catecholamine?Thanks.
What is the exact connection? They are both metabolized by MAOa that is inhibited. Tyramine is a neurotransmitter that causes increase in BP. Tyramine also increases the release of D and NE from presynaptic vesicles by DISPLACEMENT. It's not by exocytosis. Anyway, this biochemistry is lrobably way beyond the scope of Step 1. The combination of these two effects leads to hypertensive crisis.

Last edited by quacky.mcquacky; 08-22-2015 at 04:32 AM.
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Old 08-22-2015
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If you're interested, try to google som articles on this topics, there are plenty of them.
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Old 08-22-2015
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Thanks quacky.mcquacky. Your explanation filled the gap that I was missing.Mechanism u mentioned is short and sweet and to the point.That is what I was looking for.
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Old 08-22-2015
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Actually, doubt arose when I was watching Express videos in which the guy was explaining - Tyramine increase catecholamine synthesis. So, want to confirm once again, tyramine increases catecholamine realease NOT synthesis, right ?(as explained by u)
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Quote:
Originally Posted by Aumsai View Post
Actually, doubt arose when I was watching Express videos in which the guy was explaining - Tyramine increase catecholamine synthesis. So, want to confirm once again, tyramine increases catecholamine realease NOT synthesis, right ?(as explained by u)
Ya its a releaser
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Old 08-22-2015
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ok, thanks mk09
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