Pharmacology of antihypertensive agents

Question 1

describe the regulation of blood pressure

Answer 1

BP = CO X TPR
cardiac output= stroke volume x heart rate
- stroke volume regulated by ventricles
- heart rate regulated by SA node

Question 2

what is total peripheral resistance and how is it regulated

Answer 2

1. measure of the degree of constriction of the arterioles
2. increases in AngII –> increases IP3 –> increase intracellular conc of Ca2+
3. causes constriction of arterioles and an increase in total peripheral resistance and an increase in blood pressure

Question 3

what is the regulation of preload

Answer 3

1. constriction of venules via AT1-R

2. RAAS also facilitates Na+ and h2o retention

Question 4

what is the role of aldosterone

Answer 4

activates cytoplasmic receptors which bind to the nucleus to increase expression of na+ channels
- so aid na+ and water retention

Question 5

what is the choice of drug treatment dependent on

Answer 5

1. age- <55 years: ACE inhibitor/angiotensin receptor blocker
   - >55 years: calcium channel blocker
2. ethnicity- ACE inhibitors/beta blockers may be less efficacious in black africans/americans
3. co existing diseases