the effect of chemicals on muscle contraction

• Chemicals can block the release of neurotransmitters or affect the way they bind to receptors on the postsynaptic membrane
• This can prevent the action potential from being passed on to the muscle, leading to the muscle not contracting
• Example: Pancuronium bromide is a non-depolarising, neuromuscular blocking drug
• Pancuronium bromide competes against ACh for nicotinic cholinergic receptors, blocking the action of ACh and preventing muscle cell depolarisation
• Pancuronium bromide is used during surgery to relax muscles
• The action of pancuronium bromide can be reversed by inhibiting AChE, increasing ACh concentration to out-compete the drug for nicotinic cholinergic receptors
• Chemicals affecting neurotransmitter action at neuromuscular junctions can be fatal if they affect breathing muscles like the diaphragm and intercostal muscles
• If these muscles can't contract, ventilation is impaired, and aerobic respiration is compromised