Pharmacology of Peripheral Neural Transmission (NANCs) Flashcards

1
Q

Which NANCs are associated with ACh neurones?

A
  1. ATP
  2. VIP
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2
Q

Which NANCs are associated with NA neurones?

A
  1. ATP
  2. NPY
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3
Q

What are the mechanisms by which NANCs can act?

A
  1. Mediates neurotransmission by binding to post-synaptic ion channels.
  2. Acts as neuromodulators by binding to post-synaptic receptors (mainly GPCRs) to change effect of NT.
  3. Act on further targets due to being broken down much more slowly.
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4
Q

What are the affinities of P1 receptors for purinergic transmitters?

A

Adenosine > AMP > ADP > ATP

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5
Q

What are the affinities of P2 receptors for purinergic transmitters?

A

ATP > ADP > AMP > Adenosine

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6
Q

What are the different classes of purinergic receptors?

A
  1. Adenosine (P1) receptors - GPCRs
  2. P2X receptors - LGICs
  3. P2Y receptors - GPCRs
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7
Q

How is ATP packaged into vesicles?

A

Vesicular nucleotide transporter (VNUT)

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8
Q

How is ATP released during transmission?

A
  1. Exocytosis from vesicles
  2. Nucleoside transporters (e.g. pannexins)
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9
Q

What is the structure of P2X receptors?

A
  • Each isoform contains 2 transmembrane domains
  • Isoforms assemble into homo-/heterotrimers to form functional recepotors
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10
Q

What is the role of P2X receptors in PNS?

A
  • ATP co-released with NA/ACh
  • Causes fast component of smooth muscle contraction (P2X) followed by slower contraction caused by NT (α-adrenoreceptor)
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11
Q

What is the role of P2X receptors in sensation?

A
  1. Important in transduction mechanisms of some special senses (e.g. taste)
  2. Important in mediating sensation of distension in bladder
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12
Q

How is adenosine produced?

A
  1. Breakdown product of ATP by ectodonucleases
  2. Produced intracellularly by endonucleases and is released if rate of production exceeds rate of metabolism
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13
Q

What is the role of adenosine in cardiac tissue?

A
  1. Produced in cardiac tissue during hypoxia
  2. Rate of production exceeds rate of metabolism
  3. Released into ECF
  4. Binds to A1 receptors and causes reduced heart rate/contractility
  5. Reduces work of heart and protects against damage
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14
Q

What is the role of NO in the PNS?

A

Nitrergic (NO-releasing) neurones mediate muscle tone of several sphincters of the GI tract (e.g. lower oesophagus, pylorus…), upper airways and male reporductive organ

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15
Q

How is neuropeptide release stimulated?

A

Repetitive APs → ↑ general [Ca2+] (as opposed to local for NTs)

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16
Q

What are the effects of neuropeptide release in autonomic ganglia?

A

Responsible for late slow EPSP