Beta2 agonist - effect on BP?

[w00tz]

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So one of my study sources says that beta2 receptors decrease blood pressure (BTW a beta2 receptor vasodilates, increases heart rate and contractility). It kinda didn't make sense to me at first, because I know that beta-blockers are used to decrease blood pressure. So if the above statement were true, blocking only beta2 receptors would actually increase blood pressure . I know it's not as simple as that, because beta-blockers also target beta1 receptors, which definitely increase blood pressure (increase HR and contractility). So I'm guessing the beta-1 blockade response trumps the beta-2 blockade in terms of blood pressure when a person is given a non-selective beta-blocker? Can anyone confirm/clarify this?

Just trying to clear this up, thanks in advance fellas!

 

[bbydoc]

So one of my study sources says that beta2 receptors decrease blood pressure (BTW a beta2 receptor vasodilates, increases heart rate and contractility). It kinda didn't make sense to me at first, because I know that beta-blockers are used to decrease blood pressure. So if the above statement were true, blocking only beta2 receptors would actually increase blood pressure . I know it's not as simple as that, because beta-blockers also target beta1 receptors, which definitely increase blood pressure (increase HR and contractility). So I'm guessing the beta-1 blockade response trumps the beta-2 blockade in terms of blood pressure when a person is given a non-selective beta-blocker? Can anyone confirm/clarify this?

Just trying to clear this up, thanks in advance fellas!

thats correct.
most of the beta receptors on the heart are beta-1 receptors btw, not beta-2.
Although decrease in HR plays a role, one of the main ways how beta-blockers decrease BP is by inhibiting Renin production in the kidney (recall: Renin producing JGA-cells have beta-1 receptors) --> decrease in ATII (one of the most potent vasoconstrictors) and decrease in Aldosterone (Na+ retention)
So you are reducing BP by reducing volume and TPR.