adrenoceptors Flashcards
what is a signalling pathway
an intracellular biochemical pathway which links the receptor to the cellular outcomes
do receptors share signalling pathways
yes
how can one receptor control many functions from one second messenger
pathways diverge as they cascade down
how does a GPCR transduce signals
it links to one or more G-protein to transduce the receptor signal to an effector enzyme/target
what does calcium binding mean
contraction in a smooth muscle environment
what does increase in cAMP lead to (b1 in heart)
an increase in protein kinases which increases calcium coming into cell
causes contraction
what do GS proteins do in airway vessels (b2)
stimulates production of cAMP which inhibits calcium release.
leads to smooth muscle relaxation
can the same signalling pathway have different effects
yes, depending on the needs of the cell type
characteristics of a1 adrenoceptors
close to NA release site
activated by neuronal and circulating NA
characteristics of a2 adrenoceptors
distant from NA release site
activated by circulating NA
negative feedback control of a2 adrenoceptors
agonist binds to the a2 sympathetic nerve site
decrease in calcium in and out of the cell
dropping calcium inhibits release of noradrenaline from N terminus
what is the functional outcome of the cell dependent on
the signalling activated by the receptor
the cell type and cellular machinery downstream of the signalling system in that cell
what do selective A1 adrenoceptor antagonists do
decrease vasoconstriction tone (PVR)
no change in HR or CO during chronic use
examples of selective A1 adrenoceptor antagonists
prazosin
doxazosin
what does activation of the b1 receptor do in heart
increase force of myocardial infraction
increase rate of contraction
excess stimulation leads to arrhythmia
