antihypertensive agents

Question 1

what is hypertension? 2

Answer 1

• persistently higher than normal blood pressure

- treatment if BP is higher than 150/95mmHg

Question 2

give an overview of the regulation of blood pressure? 4

Answer 2

• BP=CO x TPR
• cardiac output= stroke volume x heart rate
• stroke volume is regulated by the SA node
• total peripheral resistance is a measure of the degree tf constriction of the arterioles

Question 3

explain extrinsic regulation? 3

Answer 3

• autonomic nervous system
• sympathetic system increase frequency and force of contraction via beta 1 receptors, leads to increased cAMP, increased Ca2+, increased rate and force of contraction
• parasympathetic system decreases frequency by decreasing cAMP via M2 receptors

Question 4

explain the regulation of total peripheral resistance? 4

Answer 4

• sympathetic nervous system
• SNS releases noradrenaline, activates alpha 1 receptor which releases IP3 which releases CA2+ leading to constriction
• SNS releases adrenaline, activating beta 2 receptors releasing cAMP causing relaxation
• increases in Ang II cause an increase in IP3 which increases intracellular Ca2+ concentration which causes constriction

Question 5

explain the regulation of preload by RAAS? 3

Answer 5

• renin-angiotensin-aldostreone system
• constriction of venules via AT1-R
• RAAS also facilitates Na+ and H2O retention as aldosterone activates cytoplasmic receptors which bind to the nucleus to increase the expression of Na+ channels

Question 6

what is a choice of drug treatment for hypertension based on? 3

Answer 6

• age (<55, ACE inhibitor/ angiotensin receptor blocker ARB) (>55 or black African/American calcium channel blocker
• Race (ACE inhibitors/beta-blockers may be less efficacious in black African/Americans)
• co-existing diseases