Pharmacology question.

HyperTension · Jan 25, 2010

Here is a pretty detailed explanation of these... http://en.wikipedia.org/wiki/Receptors,_adrenergic,_alpha

The problem you will run into is there really isn't a "simple explantion". Well.. there is, but it's really not worth it especially if your giving medications that activitate / antagonize said receptor.

kwantiko · Jan 25, 2010

for Beta: You have 1 heart (Beta 1) and 2 Lungs (Beta 2)

aCRNAhopeful · Jan 25, 2010

When you say "the difference between alpha and beta receptors" the answer isn't going to make sense because, like you said, their are alpha 1 and alpha 2 receptors as well as beta 1 and beta 2. So just consider each one individually. Of course all of the receptors mentioned are part of the SNS so you would need to have an understanding of the autonomic nervous system. Those receptors are present in many different organs and tissues in the body so their effects cant be summarized easily. However, for the purpose of cardiac meds we can summarize. Drugs that stimulate Beta 1 - increase HR and contractility. Beta 2 - bronchodilation, dilation of vessels that are key to "fight or flight" (ie coronary arteries). Alpha 1 - vasoconstriction, for example phenylephrine stimulates alpha 1s and causes vasoconstriction without directly effecting the heart. And Alpha 2 - I believe these actually decrease the effects of the SNS to sort of keep it in check, meds that may stimulate these would decrease BP (ie - hydralazine, i think). Like I said there are probably a million other effects that these receptors have and thats my explaination of them without referencing any sort of textbook so take it for what its worth. Anyone feel free to correct me or add to that if you want.

souhaiel78cheb · Jan 25, 2010

hi all! can anyone explain to me in easy to understand terms the difference in alpha and beta receptors? alpha 1 vs alpha 2??? what do i really need to know in order to competently and safely hang or push these cardiac meds.
any help would be so appreciated.
omaharn

read this, i bet it will make sense....

here is the scoop about alpha1 and alpha2 receptors, alpha1 receptors are what you need to remember the most, if you take the boards you probably won't be asked about alpha 2 blocker at all. alpha 1 receptors exist in blood vessels they are cells that act as baroreceptors and cause smooth muscle of arteries(not veins because veins do not have much of smooth muscles on their walls,they work by way of valves) to contract causing hypertension (this true allways in any case where the sympathetic nervous system is stimulated by stress,substances(crack,cigarettes...)). now think of a drug that acts to block these alpha receptors, when you block these receptors this decreases hypertension, in other words less contractions of smooth muscles of arteries lining occur, this in turn can lead to hypotension = eeh less hypertension which means watch out for hypotension (like a balance, get it! lol). now when i say alpha one receptors are in smooth muscles they are mainly in arteries and in the bladder as well.this mean when you block these receptors, the bladder contraction is blocked=bladder relaxed, you may think oh urinary retention,but not too fast,there are also alpha1 receptors in the prostatic sphincter at the neck of the bladder which when blocked,makes this sphincter relax and urine is allowed out of bladder(allthough the bladder is not contracting), this is what the drug hytrin do exactly and it is used for bph. now the thing is that most alpha 1 blocker drugs do not discriminate between alpha 1 receptor sites ,they block any alpha 1 receptors they encounter in the body (mainly arteries and bladder). so long story short, what need to remember is alpha1 blockers cause hypotension and they act mainly on arteries and bladder.

now, you may think what about alpha 2 receptors, well these guys mainly decrease the pancreas production of insulin and increase its production of glucagon,they are also located in the gi tract sphincter and when stimulated cause contraction of gi sphincters. so when you block this receptors ( in pancreas and gi sphincters), you increase the production of insulin from the pancreas and decrease that of glucagon.also alpha 2 blockers block gi sphincter= you get the rest (bunch of constipation,bloating......).

alos keep in mind there are drugs that block both alpha1 and alpha 2 at the same time.

for the beta blocker, read the previous posts, i saw one that looked good.

i hope i didn't confuse with this lengthy explanation, hey if there was an easy way to remember this s.h.t everyone would have became an rn lol. any way just remember alpha1 blockers and froget about alpha 2 blockers , you probably won't see them at all, they are mainly used in research.

omaharn · Jan 26, 2010

Hi All! Can anyone explain to me in easy to understand terms the difference in alpha and beta receptors? Alpha 1 vs Alpha 2??? What do I really need to know in order to competently and safely hang or push these cardiac meds.
Any help would be so appreciated.
OmahaRN

Thanks to you all for your responses!! They were all very helpful!!

XingtheBBB, BSN, RN · Jan 26, 2010

And Alpha 2 - I believe these actually decrease the effects of the SNS to sort of keep it in check, meds that may stimulate these would decrease BP (ie - hydralazine, i think).

I think I'll have more to add later. When I have more time. Just wanted to say hydralazine may or may not have alpha 2 effects. Probably, along with effects at.... ??? The science behind it is still up for grabs. (hmmm... now I'm putting that on my reading list) Clonidine is the known alpha 2 agonist used for BP (again, the only SNS receptor that lowers BP when agonized) The other alpha 2 agonist we use a lot in ICU's... is... Precedex. Apparently Precedex also raises natural catecholamine levels so you shouldn't loose too much pressure with it, but if you do, you know why