2.03 - Pharmacological Determinants Of Peripheral Vascular Resistance

Question 1

What are the three mechanisms for modulation of vascule tone? Provide examples for each

Answer 1

Neural Control: sympathetic and parasympathetic. However very few vessels outside of the CNS are directly innvervated by the PNS

Humoral Control: Hormones via the blood system. Include - angiotensin, alodsterone, adrenaline, noradrenaline vasopressin, endothelin

Local control: Metabolites. E.g. NO, Prostaglandin etc.

Question 2

What are some drug groups that reduce vascular tone?

Answer 2

Sympatholtics

Calcium channel blockers (nifedipine)

ACE Inhibitors (captoril)

AT1R antagonists (candesartan, losartan)

Vasodilators (nitroprusside)

Question 3

Compare the relative potency of adrenaline, noradrenaline and isoproterenol at alpha, beta1 and beta2 receptors

Answer 3

Alpha: Adrenaline > Noradrenaline >> Isoproterenol

Beta1: Iso > Adrenaline > Noradrenaline

Beta2: Iso > A > NA

Question 4

What adrenceptor is in the heart at what affect does it have?

Answer 4

Beta1

Increase in heart rate, contractility, conduction velocity and automaticity

Question 5

What adrenceptors are in arterioles and what effect do they have?

Answer 5

alpha (constriction) and beta2 (dilation)

Question 6

What adrenceptors are in the venous system and what effect do they have?

Answer 6

alpha (constriction) and beta2 (dilation)

Question 7

Compare and contrast the alpha1 and alpha2 adrenceptors with regrads to:

Subtypes, location, G-protein activated, signalling cascade, molecular effect and function

Answer 7

Question 8

Compare and contrast beta1 and beta2 receptors, with regards to location, g-protein activated, signalling cascade, molecular effect, function

Answer 8

Question 9

What are alpha agonists used for clinically?

Answer 9

Decongestive nasal sprays

Question 10

What are beta2 receptor agonists used for?

Answer 10

Bronchodilation sprays in asthma

Question 11

what are alpha antagonists used for clinically?

Answer 11

hypotension, uteral contractions

Question 12

What are beta antagonists used for clinically?

Answer 12

Hypertension (indirect effect), tachycardia

Question 13

Describe the concept of haemodynamic steal

Answer 13

Atherosclerotic plaques hinder vasomotion

Vasodilation reduces resistance in each vascular arm and so increases flow in these areas

Because resistance around sclerotic plaques does not change much, blood finds easier flow paths, thereby reducing flow over plaque: “haemodynamic steal”.

Vasodilation in pathological vessels may therefore result in worsened perfusion