Patient: Beta Adrenoceptors Flashcards Preview

Pharmacy Year 2 Semester 1 > Patient: Beta Adrenoceptors > Flashcards

Flashcards in Patient: Beta Adrenoceptors Deck (18):
1

Describe the binding when beta1 and beta2 adrenoceptors are activated

GPCR
Galphas activates adenylyl cyclase
Increase in cAMP
increase in PKA (protein kinase A)

2

Describe the functional response when a beta1 adrenoceptor is activated

1) Heart: SA node, AV node, Myocardium
Increase HR
Decrease refractory period
Increase force of contraction

2) Juxtaglomerula cells - release of renin
3) GI smooth muscle relaxtion

3

Describe the functional response when a beta2 adrenoceptor is activated

1) Bronchodilation
2) Vasodilation
3) GI smooth muscle relaxation
4) Relaxation of visceral smooth muscle
5) Decrease in histamine release
6) Muscle Tremor
7) Glycogenolysis

4

Beta2 adrenoceptor activation: vasodilations effects?

-skeletal muscle vasculature
-endothelium-dependent
-release of Nitric Oxide (NO)

5

beta2 adrenoceptor activation: Relaxation of visceral smooth muscle effects?

-Bladder detrusor
-ciliary muscle
-seminal tract
-uterus (premature labour)

6

beta2 adrenoceptor activation: Glycogenolysis occurs where?

Hepatocytes and skeletal muscle

7

Functional response of beta3 adrenoceptors

Lipolysis (breakdown of fat) on adipocytes

8

Name beta2-selective agonists used as bronchodilator agents

Short acting (2-4 hours)
Salbutamol and terbutaline

Long acting (up to 12 hours)
Salmeterol and efortmoterol

9

Unwanted effects of beta-agonist bronchodilators

1) Tremor - peripheral effect involving interference with muscle spindle function
2) Tachycardia - activation of cardiac beta-AR
3) Nervous tension - effect on CNS
4) Hypokalaemia - stimulation of Na+/K+ ATPase in skeletal muscle

10

How are unwanted effects of beta-agonist bronchodilators reduced?

inhalational rather than oral administration

11

Name another use of a b-adrenoceptor agonist apart from bronchodilators

Supression of premature labour (tocolysis)
e.g. salbutamol or ritodrine
which are both beta2-selective agonists

12

Give 3 properties of Propranolol

-competitive agonist
-Non-selective Beta-adrenoceptor antagonist
-Relatively lipid soluble (good penetration of CNS)

13

Give 3 properties of Atenolol

-Competitive antagonist
-relatively selective beta1-adrenoceptor anatagonist
-relatively water soluble (poor penetration of CNS)

14

Give a use of beta-adrenoceptor antagonist
How does it work?

Anti-hypertensive drugs
Decrease in: cardiac output, renin release and sympathetic tone (vasomotor centre in medulla oblongata)

15

What is angina pectoris and how are beta-adrenoceptors used in its prophylaxis?

Angina of effort: crushing pain in chest that may radiate to arm, neck or jaw.
The pain results from cardiac ishaemia
Cardiac Beta1-AR blockade (propranolol)
-decreases cardiac rate, force and work
-prolongs diastole (bradycardia)
-increases coronary blood flow
-increases 02 delivery

16

How are B-AR antagonists used to control symptoms of thryotoxicosis

Thyroid hormone sensitises tissues to catecholamines (hence eyelid contraction occurs)
Symptoms that can be controlled by beta-blocker e.g. propanolol:
-Anxiety, tachycardia, Palpitations, tremor

17

Propanolol (beta-AR anatagonist) can be used for the prophylaxis of what other thing? (not cardiac)

Prophylaxis of migraine
Mechanism unclear but may involve anxiolysis (inhibits anxiety)

18

Unwanted effects of Beta-AR antagonists

1) Bronchoconstriction
-bronchial ashtma
-bronchitis
-emphysema
2) Precipitation of cardiac failure/heart block
-patients with heart disease
-oxprenolol (partial agonist)
3) Hypoglycaemia
-patients with diabetes
-mask of sympathetic sweating, tachycardia and tremor
4) Cold extremities
-Raynaud's disease and claudication
5) vivid dreams
-propanolol (practolol)
-not a problem with atenolol