The nurse administers a drug that stimulate the parasympathetic nervous system. What physiologic response would indicate that the drug is working?

A) Are no longer approved for treating depression: MAO inhibitors (MAOIs) are still approved and used to treat depression, especially in cases where other medications have not been effective. They are not considered obsolete, though their use has become less common due to the availability of safer, more tolerable options. This is not the primary reason why MAOIs may not be prescribed.

B) Are more expensive than other antidepressants: While cost can be a factor in medication choice, it is not the primary reason why MAO inhibitors are less frequently prescribed for depression. There are other more significant concerns, such as side effects and dietary restrictions, that make other medications a preferred first-line choice.

C) Require strict dietary restrictions: This is the most accurate explanation. MAO inhibitors can cause dangerous interactions with certain foods that contain high levels of tyramine, such as aged cheeses, cured meats, and fermented products. Consuming these foods while on an MAOI can lead to a hypertensive crisis, which is a life-threatening condition. Because of these dietary restrictions, patients on MAOIs must adhere to a strict diet, which can be challenging to manage.

D) Can cause profound hypotension: While hypotension can occur as a side effect of MAOIs, it is not the most significant concern. The more serious risk with MAOIs is the potential for a hypertensive crisis due to dietary interactions with tyramine-containing foods, rather than hypotension. Therefore, the dietary restrictions are a more pressing issue than the risk of hypotension.

A) Beta 1-receptors:
Beta 1-receptors are primarily found in the heart, and their stimulation leads to increased heart rate and contractility. These receptors are not typically involved in vasoconstriction, pupil dilation, or piloerection.

B) Beta 2-receptors:
Beta 2-receptors are primarily located in smooth muscles such as the bronchi and blood vessels. Their stimulation causes smooth muscle relaxation, leading to bronchodilation and vasodilation. Beta 2-receptors are not responsible for the effects of vasoconstriction, piloerection, or pupil dilation described in the question, making this option incorrect.

C) Alpha 2-receptors:
Alpha 2-receptors are involved in the inhibition of norepinephrine release and play a role in regulating sympathetic tone. They are not primarily responsible for vasoconstriction or the other physiological responses listed in the question. Alpha 2-stimulation typically results in decreased sympathetic activity, not the effects described here.

D) Alpha 1-receptors:
Alpha 1-receptors are located on smooth muscle, including the blood vessels, and their stimulation results in vasoconstriction. They are also involved in other actions such as piloerection (hair standing on end), pupil dilation (mydriasis), and closure of the salivary sphincter. Additionally, they play a role in male sexual emission (ejaculation). The physiological responses described in the question—vasoconstriction, piloerection, pupil dilation, and male sexual emission—are all consistent with alpha 1-receptor stimulation.