Which of the following best describes the mechanism of action of d-Tubocurarine?
D-tubocurarine is the prototype Non-depolarising neuromuscular blocking agents that causes a Competitive, non-depolarising block at Nicotinic (Nm) cholinergic receptors. Mechanism of Action of d-Tubocurarine and other Non-Depolarising Competitive Blockers: At low doses (Competitive Block) At high doses (Complete Blockage) At low doses (typical doses) Non-depolarising agents competitively block ACh at the nicotinic receptors. They compete with ACh at the receptor without stimulating it. Thus, these drugs prevent depolarization of the muscle cell membrane and inhibit muscular contraction. At high doses (Atypical doses) Non depolarising agents can also block the ion channels of the motor endplate Their competitive action can be overcome by administration of cholinestrase inhibitors, such as neostigmine and edrophonium, which increase the concentration of ACh in the neuromuscular junction At high doses with blockage of ion channels the abiility of ACh-esterase inhibitors to reverse the action is significantly reduced. At low doses, the muscle will respond to direct electrical stimulation from a peripheral nerve stimulator to varying degrees. This allows for monitoring of the extent of neuromuscular blockade With complete blockade, the muscle does not respond to direct electrical stimulation from a peripheral nerve stimulator Doesnot allow monitoring Ref: KDT 7th edition Pgno: 347
Competitive, non-depolarising block at Nm cholinergic receptors
Competitive , depolarising block at Nm cholinergic receptors
Non-competitive, non-depolarising block at Nm cholinergic receptors
Non-competitive, depolarising block at Nm cholinergic receptors
Autonomic nervous system