A research compound selectively blocks ganglionic nicotinic receptors (Nn subtype) but not neuromuscular nicotinic receptors (Nm subtype). The expected clinical effect would primarily be:

• A Skeletal muscle paralysis
• B Enhanced neuromuscular transmission
• C Autonomic ganglionic blockade causing orthostatic hypotension ✓
• D Selective mydriasis without cycloplegia

Explanation

Nn (neuronal-type) nicotinic receptors are located at autonomic ganglia and the adrenal medulla, whereas Nm (muscle-type) receptors are at the neuromuscular junction. Selective Nn blockade interrupts both sympathetic and parasympathetic ganglionic transmission, leading to ganglionic blockade syndrome — orthostatic hypotension, tachycardia (due to loss of vagal tone), constipation, urinary retention, and xerostomia. Hexamethonium was the prototype ganglionic blocker.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.