predominant tone of arterioles

[Zzmed]

Here is what it confuses me:

Predominant tone of arterioles is sympathetic and especially beta2---> vasodilation.

I've read that hexamethonium (nicotinic ganglion blocker) blocks predominant tone of arterioles (sympathetic) and of heart (parasympathetic). So it decreases BP and increases HR.
I get the HR. But I can't understand how decreased BP occurs from hexamethonium MOA..

---

Members don't see this ad.

 

[Charles_Carmichael]

Predominant tone is alpha-1. Not beta-2.

Remember, beta-2 receptors are not innervated -- they need circulating epinephrine to activate them. Not only that, beta-2 receptors don't respond to norepinephrine, even if you inject it into a patient.

So, the normal tone of the vasculature is predominantly alpha-1-mediated. When you take away this tone with a ganglion blocker, you get vasodilation and a drop in MAP. Make sense?

 

[Zzmed]

Mmm... probably I got the whole thing wrong from the beginning.
What you say makes sense! Thanks.
I have annotated that beta2 predominate in the vasculature of skeletal muscles. Which has nothing to do with MAP. Right?