essential pharmacology mw%% (+

Question 1

Describe the basic functions of receptors?

Answer 1

o Enable specificity

o Evokes an appropriate response

–membrane permeability

–metabolism

–secretory activity

–rate of proliferation or differentiation

–contractile activity

–this process is called signal transduction

Question 2

Steroid hormones

Answer 2

• Are lipid soluble
• Bind to intracellular receptors
• Often a transcription factor in the nucleus
• Alters rate of transcription

Question 3

NO

Answer 3

• Lipid soluble
• Binds to soluble guanylyl cyclase
• Generates cGMP as a 2• messenger which regulates cell activity

Question 4

Define what is meant by a receptor?

Answer 4

Receptors are proteins that recognise a specific compound or molecule. This can result in the triggering of a massive variety of effects, or in some cases, can inhibit the effects of their proteins and chemicals.

Question 5

Plasma Membrane Receptors

Answer 5

• Receptors that act as ion channels
• Receptors with intrinsic enzyme activity
• Receptors that interact with JAK kinases
• Receptors that interact with G-proteins: biggest group, with several sub-families

Question 6

G-protein Coupled Receptors (Aden C)

Answer 6

Coupled to adenylyl cyclase:

• Increases/ decreases cAMP (2nd messenger)
• Activates/ inhibits PKA (protein kinase A)

Question 7

G-protein Coupled Receptors 2 (Phos C)

Answer 7

Coupled to phospholipase C:

• Produces diacylglycerol and inositol trisphosphate
• Activates PKC and releases Ca²⁺ from internal stores

Question 8

G-protein Coupled Receptors 3 (ion)

Answer 8

Coupled directly to ion channels:

• Evoke slow EPSPs and slow IPSPs.

Question 9

Define the sources of intracellular calcium?

Answer 9

o From internal stores via calcium triggered release from endoplasmic reticulum

o From outside the cell via ligand-gated or voltage-gated channels

o Via inhibition of Ca²⁺ transport out of the cell

Question 10

Explain the terms agonist and antagonist?

Answer 10

• Agonists mimic the normal effect of a receptor
• Antagonists block the normal action of a receptor

Question 11

Describe the relationship between agonist concentration and effect?

Answer 11

• As we increase the concentration of the agonist molecule, more receptors are activated and so you get a bigger response.
• This only works until a certain point before all of the receptors become saturated, and after this, if you add more nothings happens because you have saturated those receptors.

Question 12

Define the term affinity of a drug for a receptor?

Answer 12

The strength of the chemical attraction between the drug and the receptor.

Question 13

Explain the idea of efficacy of an agonist?

Answer 13

• How good an agonist is at activating the particular receptor.
• The agonist can fully activate the recpetor or partially activate the receptor.

Question 14

The lock & key hypothesis:
the basis of selectivity

Answer 14

1 transmitter may act on several receptor subtypes

–eg ACh - the endogenous agonist is the “master key” which activates all cholinergic receptors, nicotinic and muscarinic

–or noradrenaline – the endogenous agonist is “master key” which activates all adrenergic receptors, a1, a2, b1, and, b2

Selective agonists activate only some of those receptors

–eg salbutamol - a b2 -agonist

Selective antagonists block only some of those receptors

–eg propranolol - a b1 and b2 -antagonist

Based on structure-activity relationships