Which medication selectively blocks N receptors at the autonomic ganglia?

Mecamylamine is the medication that selectively blocks nicotinic (N) receptors at the autonomic ganglia. This action leads to the inhibition of neurotransmission at these sites, effectively disrupting communication between the preganglionic and postganglionic neurons in the autonomic nervous system. Mecamylamine functions as a non-depolarizing ganglionic blocker and is primarily used for its effects on blood pressure and in the treatment of hypertension, particularly in urgent scenarios.

Understanding the role of nicotinic receptors is crucial here. These receptors are abundant at the autonomic ganglia and mediate transmission from the preganglionic neurons that release acetylcholine. By blocking these receptors, mecamylamine prevents the endogenous acetylcholine from activating transmission, leading to a decrease in sympathetic and parasympathetic outflow.

The other options include substances with different mechanisms: atropine is a muscarinic antagonist that mainly affects parasympathetic responses; curare blocks nicotinic receptors at the neuromuscular junction, which has implications for skeletal muscle function rather than at autonomic ganglia; and succinylcholine is a depolarizing neuromuscular blocker that affects skeletal muscle transmission but does not act at