Which action is not an action of cholinergic drugs?

Correct option is C

Sol. Cholinergic drugs (parasympathomimetics) mimic the effects of acetylcholine, primarily stimulating the parasympathetic nervous system (PNS). They cause pupil constriction (miosis), increased salivation, and reduced heart rate. However, they typically increase the tone of smooth muscles, not decrease it.
Explanation of Each Option:
· Constriction of pupil: Cholinergic drugs stimulate the parasympathetic nervous system, leading to miosis (pupil constriction).
· Enhance salivary secretion: Correct; these drugs increase glandular secretions, including saliva and digestive enzymes.
· Decrease tone of smooth muscle: Incorrect answer; cholinergic drugs generally increase smooth muscle tone, leading to effects like bronchoconstriction and increased peristalsis.
· Reduce heart rate: Correct; these drugs activate the vagus nerve, slowing down the heart rate (bradycardia).