Propanolol a Beta Blocker for High BP?

[motorcycletunes]

I like to keep things simple then build on them, but I think I may have over simplified this too much or something.

Alpha 1 - vasoconstrictor

Alpha 2 - vaso dilator

Beta 1 - Heart

Beta 2 - lungs

So lets say that low BP is treated with Epinephrine, blocking alpha 1, so that the arteries dilate lowering the BP

Now lets say that High BP is treated with Propanolol (nonselective beta blocker) the inturn lowers the BP.

I was thinking BP would always be on the Alpha, and Heart Rate would be I know the heart can affect BP, and so can the vasoconstriction, so would propanolol for BP be a secondary use of the drug? I assume the problem to be the bloodpressure and not the heart, but if the problem was the heart causing the bp then it would make perfect sense.

I just don't understand whey approach low BP from the Beta side, instead of the alpha side.

[Meeshie]

The really simple answer is that there are vasodilators that treat elevated BP - but they are not usually considered first line therapies (except in certain very specific circumstances). You'll see them prescribed more often in patients with heart failure,for example. Some third gen beta blockers also vasodilate.

The paper I'm linking is about the difference between the drugs and uses in hypertensive treatments. Enjoy: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.604.8250&rep=rep1&type=pdf

[umbdude, MSN, APRN]

Epinephrine is a vasopressor so it does not dilate vessels but constricts them; it also stimulates other sympathetic receptors.

BP is a function of cardiac output (CO) & systemic vascular resistance (SVR). CO depends on HR & stroke volume (volume of blood pumped). So, lowering HR and contractility (i.e. propanolol) lowers CO, which in turns lowers BP. Non-selective beta blocker like propanolol could cause bronchoconstriction and peripheral vasoconstriction (these are side effects).

Both alpha & beta blockers could lower BP and are used, but I don't know the detailed reason why one is used more often than another. It could be because alpha blockers have more side effects (imagine relaxing all your arteries and veins) and what med to use could vary from one individual to another.

As far as I know (from books & personal experience), first-line drug for HTN is usually a hydrochlorothiazide, if that doesn't work, then ACE inhibitors, then beta blockers and calcium blockers etc. Normally from meds with fewest side effects.