Beta 2 agonist side effects. Increase blood pressure?

[KevinEMT]

A beta 2 agonist relaxes muscles (bronchodilates) and a side effect is tachycardia because it mimics the sympathetic nervous system. We had a test question that asked if a beta 2 agonist would cause?
a. increase heart rate
b. increase heart rate and an increase inblood pressure
c. decrease heart rate
d. decrease heart rate and increase in blood pressure

Everywhere I look just says tachycardia, but I am thinking too hard that it would increase blood pressure because of the tachycardia?

 

[Aprz]

beta 2 agonist relaxes muscles

Wouldn't you consider blood vessels to be smooth muscles? If they were to relax for whatever reason, what would happen to the heart rate to help compensate for this relaxation?

 

[Gurby]

I never thought about it like this, I guess.... Is that the whole reason beta agonists increases heart rate at all? They cause vasodilation and then the tachycardia is a compensating measure? Crazy!

 

[EpiEMS]

They cause vasodilation and then the tachycardia is a compensating measure? Crazy!

I blame the EMT educational standards...

 

[Carlos Danger]

There are beta 2 receptors in the SA node, but their ability to increase HR is weak compared to stimulation of the B1 receptors.

The tachycardia that you see when you give albuterol, for instance, is probably primarily due to the fact that, even though albuterol is primarily a B2 agonist, it also has some action at the B1 receptors.

Few drugs are really highly specific to a particular receptor subtype.

 

[CWATT]

There are beta 2 receptors in the SA node, but their ability to increase HR is weak compared to stimulation of the B1 receptors.

The tachycardia that you see when you give albuterol, for instance, is probably primarily due to the fact that, even though albuterol is primarily a B2 agonist, it also has some action at the B1 receptors.

Few drugs are really highly specific to a particular receptor subtype.

This. Some areas contradict Albuterol in presence of tachydysrhythmias due to its non Beta-2 selective nature in high concentrations.