CV Pharm-Anti Hypertensives Flashcards
What are the effects of the sympathetic nervous system in HTN?
- Via Barometric reflex
- increases HR
- Vasoconstriction
Where does AT act to produce hypervolemia via retention of Na and H2O?
Proximal tubule
What is the neurotransmitter of the sympathetic nervous system?
Norepi
Which receptors does Norepinephrine act on?
Alpha adrenergic & Beta Adrenergic
What type of receptors are the Angiotensin receptors and Alpha adrenergic receptors?
These are GQ coupled receptors, whose activation results in the release of Phospholipase C which acts on PIP2 to create DAG & IP3 which results in release of Calcium from the SR
Where are the Alpha Adrenergic and ATII receptors primarily?
In Smooth muscle (VSM) cells
What kind of receptors are in the heart cells?
Beta Adrenergic receptors
What are the Beta Adrenergic receptors coupled to?
GS coupled
What does activation of the Beta Adrenergic receptors result in?
Activation of Adenylate cyclase which converts ATP to cAMP which the activates the L-Type Calcium channels via PK-A
Where is Epinephrine made?
Adrenal Medulla
What are the predominant receptors in the heart and Lung?
B1 in the Heart
B2 in the Lung
What are the effects of NorEpi after binding with Beta1 receptors in the heart?
- Increase of force of myocardial contraction
- Increase in HR
- Increase in the rate of myocardial relaxation
What is the major receptor upon which norepi acts in peripheral blood vessels?
Alpha 1 receptors (including in the kidney)
What is the effect of norepi action on PBV?
Increase in systolic and diastolic Pressures
Which causes the greater vasoconstriction Norepi or Epi and why?
Norepinephrine because it does not induce compensatory vasodilation via Beta2 receptors on blood vessels supplying skeletal muscle
What are the peripheral vessels most acted on by the sympathetic nervous system?
- Precapillary arterioles
2. Venules
What is the function of the Alpha2 receptors in the presynaptic cleft?
To feedback inhibit the release of norepi
How is adrenergic receptor signalling terminated?
By Uptake 1 of the transmitter usually by the presynaptic neuron
How does Reserpine work?
Inhibits (uptake 2) VMAT the transporter of Dopamine and Norepi into transmitter vesicles of adrenergic nerves
What is the effect of reserpine?
TPR is reduced due to the highly reduced amount of norepi to act on Alpha receptors
How is reserpine administered?
.5mg Orally
What are the side effects of Reserpine?
Sedation and mental depression
When is reserpine contraindicated?
- In patients with a history of mental depression (increases suicidal tendencies)
- In patients with a history of Duodenal ulcers
What is the mechanism of action of the alpha 1 selective blockers (osin)
Block the peripheral alpha 1 receptors (mostly on arterioles and venules)