Nitrates and Baroreceptor Relfex

[dextor2003]

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This table in the FA 2015 says that nitrates have no effect on contractility, yet they increase heart rate via the baroreceptor reflex. Doesn't the reflex also increase contractility, though?

 

[Transposony]

This table in the FA 2015 says that nitrates have no effect on contractility, yet they increase heart rate via the baroreceptor reflex. Doesn't the reflex also increase contractility, though?

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I think they are talking about DIRECT effect.

 

[dextor2003]

I think they are talking about DIRECT effect.

But then why is the increase in HR shown as a reflex response?

 

[Transposony]

But then why is the increase in HR shown as a reflex response?

That's why they specified that it is a reflex response and not a direct action.

 

[dextor2003]

That's why they specified that it is a reflex response and not a direct action.

I guess I was just thinking it would've made more sense for them to show both as either direct or reflex responses, and not direct for one and reflex for the other. Oh well. Thanks though.

 

[Transposony]

I guess I was just thinking it would've made more sense for them to show both as either direct or reflex responses, and not direct for one and reflex for the other. Oh well. Thanks though.

I think what the take home message for us is that nitrates mainly causes reflex tachycardia and although it also causes +ve inotropy via sympathetic stimulation it is not as significant as reflex tachycardia.
Being one of the crowdproofers for FA 2015, I realized that a lot of thought and discussion goes into every single word in FA.
Believe me, hundreds of people must have fought over this table during different stages of crowdproofing.
They try their best to keep the FA barebone but sometimes it make it difficult to understand the finer points.

 

[seminoma]

I guess I was just thinking it would've made more sense for them to show both as either direct or reflex responses, and not direct for one and reflex for the other. Oh well. Thanks though.

I know what you mean. I think they mention the reflex tachy because they consider it to be HY enough to mention. The reflex response in contractility probably isn't tested as often so they didn't bother mentioning it.

 

[seminoma]

Also I just did a question in Rx that references this table (for beta blockers) and the correct answer reflects what FA2014 says, NOT what FA2015 says. I reported it, but we'll see what happens.

 

[dextor2003]

Also I just did a question in Rx that references this table (for beta blockers) and the correct answer reflects what FA2014 says, NOT what FA2015 says. I reported it, but we'll see what happens.

cool, thanks for the heads up

 

[Transposony]

Also I just did a question in Rx that references this table (for beta blockers) and the correct answer reflects what FA2014 says, NOT what FA2015 says. I reported it, but we'll see what happens.

QBanks are always behind ...........unless they messed up the arrows 2015.

 

[seminoma]

QBanks are always behind ...........unless they messed up the arrows 2015.

I think they messed up the arrows in 2015 (it says beta blockers have no effect/decrease EDV). If the qbank was wrong I'm sure it would've been reported as errata a long time ago.