B1 Pharmacological signaling

Question 1

why do cell signal to one another

Answer 1

communication

achieve co-ordination w/in the organism where many bodily functions are orchestrated.

Question 2

name and describe 4 types of cell signaling

Answer 2

1. direct contact - gap junctions
2. synaptic signaling - neurotransmitters released, propagate & bind target cell.
3. paracrine chemical mediators - signal secreted to adjacent cells.
4. endocrine - hormone secreted into blood by endocrine gland

Question 3

Name 4 types of cell receptors

Answer 3

1. Ligand gated ion channels (ionotropic)
   e. g. Nicotinic acetylcholine receptor
2. GPCR (metabotropic)
   e. g. Muscarinic ach, beta adrenergic
3. Kinase linked receptors
   e. g. growth factors/cytokines
4. Nuclear receptors
   e. g. oestrogen

Question 4

what are the 4 major classes of GPCR

Answer 4

1. Rhodopsin family - receptor for ~amines, neurotransmitters, ~neuropeptides, purines, prostanoids, cannabinoids
2. Secretin family - receptors for peptide hormones: secretin, glucagon, calcitonin
3. Metabotropic family - glutamate receptors,, GABAb, Ca sensing receptors
4. Pheromones: NO pharmacological receptors

Question 5

what is the rate of chemical cycling liked to?

Answer 5

linked to efficacy of agonist. more cycling = increased efficacy

Question 6

what is the affinity of the agonist/antagonist dependent on?

Answer 6

the no. of interactions between the ligand & receptor (H-bonds, Pi stacking, Van der Waals forces.)

Question 7

give some examples of receptors that are linked to the activation of adenylyl cyclase.

Answer 7

beta-adrenoceptors, H2 histamine, Prostacyclin (PG12), Prostaglandin E2 (PGE2) receptors
all promote cAMP formation & PKA activation + opening of Ca channels via Gs

Question 8

give example of some receptors which inhibit adenylyl cyclase

Answer 8

alpha2-adrenoceptors and M2 muscarinic receptors.

open K channels via Gi

Question 9

give example of some receptors which activate Phospholipase C

Answer 9

M3 muscarinic receptors which activate phospholipase C

(InsP3 which mobilises intracellular calcium inside the cell, and DAG which activates protein kinase C) via Gq

Question 10

name 4 targets for G proteins

Answer 10

1. Adenylyl cyclase
2. Phospholipase C
3. Rho A/Rho kinase: controls activity of many signaling pathways controlling cell growth & proliferation, smooth muscle contraction
4. MAP kinase: controls many cell functions e.g. cell division

Question 11

activation of adenylyl cyclase results in

Answer 11

cAMP –> PKA

1. Increased lipolysis
2. Reduced glycogen synthesis
3. increased glycogen breakdown (via phosphorylase kinase –> activating phosphorylase a = glucose 1-phosphate

Question 12

what drug is inositol 1-phosphate inhibited by

Answer 12

Lithium - used as an antidepressant