Final answer:
An α2 adrenergic receptor agonist typically reduces blood pressure by inhibiting norepinephrine release, leading to lesser vasoconstriction and a decreased heart rate.
Step-by-step explanation:
When a patient is given a drug that is an α2 adrenergic receptor agonist, the effect on blood pressure is typically a decrease. This is because α2 adrenergic receptors are located in the pre-synaptic cleft of noradrenergic neurons and their activation leads to a decrease in norepinephrine release. Since norepinephrine acts to raise blood pressure by causing vasoconstriction and increasing heart rate, its decreased release due to α2 receptor agonism results in lower blood pressure.
Contrastingly, α₁ adrenergic receptors when activated cause vasoconstriction and thus, an increase in blood pressure, but this is not relevant to α2 agonists. It is important to note that α₂ adrenergic receptor agonists produce an effect opposite to that of the sympathetic fight-or-flight response, which includes increased heart rate and dilation of the pupils.
An α2 adrenergic receptor agonist will generally cause a decrease in blood pressure due to inhibition of norepinephrine release, which would otherwise increase blood pressure through vasoconstriction and heart rate elevation.