Question

a. what effect would have the blockade of voltage gated Na+ channels?

b. what effect would have the opening of chemically-gated Cl- channels?

c. what effect does voltage and chemically gated have in common?

d. what final effect do you expect to see when either local or general anesthetics are administered?

Answer 1

a) Voltage gated sodium channels are of immense importance in conduction of nerve impulse because they monitor and regulate the exchange of sodium ions between extracellular and intracellular spaces. Blockade of sodium channels can be lethal as they lead to termination of action potential. The toxins that result in blocade of voltage gated sodium channnels are mu-conotoxins, saxitoxin and tetrodotoxin.

b) Chloride channels are proteins that regulate the transport of chloride ions through cell membrane. Neurotransmitters such as GABA result in opening of chloride channels, thus allowing the movement of chloride ions inside the neuron and results in hyperpolarization of neurons

c) Both voltage and chemically gated channels help in generation and conduction of action potentials.

d) Local or general anesthetics are applied topically or by injection and act directly on neuronal sodium channels. They function by blocking nerve conduction and hence block sensation in the area innervated by affected nerve fibres