Regulating neuronal excitability

Question 1

What is the mechanism of NA reuptake?

Answer 1

90% is presynaptic neurons and repackaged into vesicles or degraded by MAO
10% taken up by the postjunctional neuron and broken down by MAO and COMT

Question 2

How does cocaine act?

Answer 2

blocks neuronal reuptake of NA, dopamine and serotonin (less taken up by presynaptic neuron) results in more NA in the synaptic cleft. Also blocks Na channels

Question 3

How do Amphetamine and Ephedrine act?

Answer 3

displace NA from the synaptic vesicles which are released via non-exocytotic mechanisms

Question 4

What are analgesic agents how do these differ from anaesthetics?

Answer 4

analgesics-> reduce/act to reduce pain
anaesthetic -> inhibit sensation/feeling of pain by reversibly blocking the condution of nerve impulses at the axonal membranes

Question 5

What are the 3 main groups of local anaesthetic agents?

Answer 5

Aminoesters (hydrophilic): procain -> short acting as they are hydrolysed by esterases
Aminoamides (lignocaine - hydrophilic) - longer acting as they are removed by hepatic metabolism.
Benzocaine (hydrophobic) -> ie in throat lozenges

Question 6

Local anaesthetics are all weak acids or bases?

Answer 6

Bases