Final answer:
Salmeterol and Dopamine are sympathomimetic agents because they stimulate the sympathetic nervous system, whereas Labetalol and Propranolol are not, as they act as ß-blockers, inhibiting the system. The correct answer is A. 1 and 2 only.
Step-by-step explanation:
The question asks which of the listed drugs are sympathomimetic agents. Sympathomimetic drugs stimulate the sympathetic nervous system by either mimicking the neurotransmitter norepinephrine or epinephrine or by increasing their production and release. On the other hand, sympatholytic drugs, also called ß-blockers, work by blocking the effects of the sympathetic nervous system, hence they are not sympathomimetic.
- Salmeterol is indeed a sympathomimetic agent as it works by stimulating ß2-adrenergic receptors in the lungs, which helps to relax the muscles in the airways and widen them, making breathing easier.
- Dopamine is a sympathomimetic because it can bind to adrenergic receptors, stimulating the heart and blood vessels.
- Labetalol, however, is both a ß-blocker and an α-blocker and therefore not a sympathomimetic agent.
- Propranolol is also a ß-blocker, which means it blocks the sympathetic nervous system rather than stimulates it. So, it is not a sympathomimetic agent either.
Therefore, the correct answer is A. 1 and 2 only, meaning that Salmeterol and Dopamine are the sympathomimetic agents among the options given.