Alpha 1 vs 2 agonists

[efageant]

Hi

I have a question in regards to the mode of action of Alpha 1 agonists vs Alpha 2 agonists. It seems as though Alpha 1 agonists are generally associated with vasoconstriction where as alpha 2 agonists are identified as vasodilators such as clonidine. Trying to understand the mechanism behind this considering that alpha 1 antagonists are also identified as anti-hypertensives. Very confusing!!

Thanks in advance

[203bravo, MSN, APRN]

Hi

I have a question in regards to the mode of action of Alpha 1 agonists vs Alpha 2 agonists. It seems as though Alpha 1 agonists are generally associated with vasoconstriction where as alpha 2 agonists are identified as vasodilators such as clonidine. Trying to understand the mechanism behind this considering that alpha 1 antagonists are also identified as anti-hypertensives. Very confusing!!

Thanks in advance

Make sure you know the difference between an agonist and antagonist when defining medications and you will have answered your own question.

Best of luck.

[umbdude, MSN, APRN]

Alpha2-receptors actually causes a negative feedback on norepinephrine (a sympathetic nervous system neurotransmitter), so by stimulating alpha 2 (agonist such as clonidine) you actually inhibits SNS and that leads to the opposite of sympathetic responses.

Alpha2-receptors also lower insulin release which is why clonidine can cause a spike in blood glucose.