Autonomic Nervous System L3

Front 1

Synthesis of NA?

Back 1

Tyrosine =tryrosine hydroxylase=> DOPA (Di hydrOxy PhenylAlanine) =DOPA decarboxylase=> Dopamine =Dopamine beta decarboxylase=> NA=> adrenaline (addition of Me)
NB NA regulate syntheis via -ve feedback on initial step of syntheis

Front 2

Drugs effecting synthesis of NA? (3)
and their mechanisms and clinical uses

Back 2

1. methyl-p-tyrosine inhibits tyrosine hydroxylase, clinical use - phaecochromocytoma
2. carbidoma inhibits DOPA decarboxylase, clinical use Parkinsons to prevent effects of levodopa (high BP, racing heart)
3. Methyldopa false precursor molecule, clinical use hypertension in pregnacy

Front 3

Unwanted effects of inhibiting NA synthesis?

Back 3

Hypotension, sedation (not with carbidopa as it dosn't enter CNS), methyldopa causes diarhoea, impotence and hypersensitivity

Front 4

Storage of NA?
Drug that prevents of NA into vesicles?

Back 4

Stored in vesicles with ATP (co-transmitter), ATP has opposite charge to NA and may help prevent leak from vesicles.
Reserpine - prevents transport of NA into vesicles leads to depletion of NA stores, used as a antihypertensive side effects similar to methyldopa but also caused depression and Parkinsonism due to CNS effects

Front 5

Regulation of NA release?
Drug that effects this?

Back 5

depolarisation of varicosities opens calcium channels stimulating release of NA by exocytosis, NA regulates its own release by activating presynaptic alpha2 R inhibiting AC preventing calcium channels opening .
Guanethidine prevents NA release , obsolete clinically also causes NA depletion i.e. hexamethionium man

Front 6

Termination of NA transmission via uptake? (2)
Vmax and affinity?

Back 6

Most of signal terminated by removal of NA from synaptic cleft.
Uptake 1 - 70% of NA is activatly transported into presynaptic nerve varicosities. High affinity, low Vmax.
Uptake 2 - NA and ATP are activly transported into postsynaptic cells and then metabolised. Low affinity, high Vmax.

Front 7

Drugs affecting NA uptake1? (2)

Back 7

1. imipramine - depression (atropine side effects)
2. cocain (sid effects hypertension, excitement, convulsions)

Front 8

Termination of NA transmission via metabolism?
(3)

Back 8

1. NA/adrenaline diffuses from synaptic cleft and transported to liver and metabolised
2. Metabolised by MAO, found in neurons, to DOMA
3. catechol-O-methyl transferase, in neuronal and nonneuronal tissue (also metabolises DOMA produced by MAO)

Front 9

Rank order of potency of NA, adrenaline and isoprenalione on alpha and beta adrenoreceptors?
from most potent to least potent

Back 9

alpha - NA>adrenaline>isoprenaline
beta - isoprenaline>adrenaline>NA

Front 10

Function of alpha1 adrenoreceptor?

Back 10

constrict most smooth muscle (except GI tract where it relaxes)

Front 11

Function of alpha2 adrenoreceptor?

Back 11

presynaptic inhibition of neurotransmitter release in both parasympathetic and sympathetic neurons

Front 12

Function of beta1 adrenoreceptors?

Back 12

Increase heart rate and force of contraction

Front 13

Function of beta2 adrenorecptors?

Back 13

Dilates/relaxes smooth muscle and increases NA release from sympathetic nerves

Front 14

Function of beta3 adrenoreceptors?

Back 14

Thermogenisis in skeletal muscle

Front 15

Affinity of NA and A for adrenoreceptors?

Back 15

A has slightly more affinity for alpha2 and beta2.
NA has slightly more affinity for alpha1 and beta1.

Front 16

Second messanger system for alpha1 receptor?

Back 16

Activates phospholipase C => DAG (activates kinase) + IP3=> Ca2+ release=> cell response

Front 17

Second messanger system for alpha2 receptor?

Back 17

Inhibits AC =>decreases cAMP, inhibition of transmitter release

Front 18

Second messanger system for beta1 receptor?

Back 18

Activates AC catalysing ATP=>cAMP=>activates kinase=>phosphorylates proteins=>cell response

Front 19

Second messanger system for beta2 receptor?

Back 19

Activates AC catalysing ATP=>cAMP=>activates kinase=>phosphorylates proteins=>cell response

Front 20

Second messanger system for beta3 receptor?

Back 20

Activates AC catalysing ATP=>cAMP=>activates kinase=>phosphorylates proteins=>cell response