Pumps And Pipes Flashcards
Which GPCR stimulated signalling pathway leads to the tonic contractions typical of vascular smooth muscle? Give 2 agonists.
The Gq stimulated PLC pathway.
NA AND ACh
What product of vascular endothelial cells is responsible for smooth muscle relaxation?
NO: L-Arg converted to NO by NO- synthase NO diffuses into cell activating sGC sCG converts GTP to cGMP cGMP activates PKG PKG stimulates SR Ca uptake, activates Ca-ATPase, inhibits Ca- voltage gated ion channels
Describe a circulating hormone and signalling pathways that causes vascular smooth muscle relaxation.
Adrenaline: Activates Gs Gs activates AC AC converts ATP to cAMP cAMP activates PKC PLC inhibits MLCK
Name a local anaesthetic labour to plasma esterases.
Procaine
Name a local anaesthetic that is metabolised in the liver.
Lidocaine
What is the local anaesthetic molecular target?
A receptor site in the inner cavity of the pore of the sodium-voltage gated ion channel
How do local anaesthetics mediate their effects?
When bound to the VGIC the influx of Na is interrupted preventing action potentials
They bind more readily to the receptor site in the activates state
What is the relationship between cardiac output, total peripheral resistance and blood pressure?
Cardiac output= pressure/resistance
What is the normal blood pressure?
110/70
What is the hypertensive blood pressure?
160/100
What is a false transmitter?
A compound which closely imitated the action of a neurotransmitter
Why would a drug with alpha agonist properties lower blood pressure?
Drugs act presynaptically, inhibiting the release of the NA, reducing the heart contraction
How do K channel openers cause vasodilation?
Minoxidil:
Block the ability of ATP to bing to the channels (so the channels open)
Opening the channels causes the membranes to hyperpolarise
Hyperpolarisation causes Ca channels to close, relaxing smooth muscle
Relaxation causes the resistance to decrease, reducing hypertension
What are the consequences of vasodilatory therapy?
Reflex tachycardia due to baroreceptor activation by beta 1 stimulation
Activates the renal angiotensin system
How are vasodilatory therapy side effects prevented?
Use beta 1 antagonists as adjuncts