Pharmacology - beta blockers

Question 1

What do BB do?

Answer 1

Block adrenergic receptors throughout the body
(blocking the action of hormones like adrenaline)
- block part of the the SNS

Question 2

What are they used to treat?

Answer 2

angina
heart failure
hypertension
heart attack
atrial fibrillation
anxiety
tremor

Question 3

What organ are they trying to work on?

Answer 3

the heart

-trying to slow it down

Question 4

What type of form of medication do BB come in?

Answer 4

Tablets

Question 5

What effect do BB have on HT and normotensive subjects when exercising?

Answer 5

Detrimental effects due to:
decreasing force and rate of heart
decreasing BP
decreasing vasodilation in SM
decreasing airway diameter
decrease muscle TG's as an energy source

Question 6

What sports may find BB useful?

Answer 6

aiming sporting

archery, javelin, shooting, darts

Question 7

What happens when the beta 1 receptor (in the heart) is activated?

Answer 7

increased cardiac function and rate which increases BP

Question 8

What happens when the beta 1 receptor is blocked?

Answer 8

inhibit the action of epinephrine and norepinephrine

reduce cardiac function and BP

Question 9

What are non selective BB?

Answer 9

Causes blockage of beta 1 and beta 2 receptors (bronchioles of the lungs and the arteries of the skeletal muscles)

Question 10

Give an example of a non selective BB?

Answer 10

propranolol
penbutolol
carteolol

Question 11

What are the implications of using a non selective BB in an asthmatic patient?

Answer 11

May not be able to dilate their airways when using their inhaler because all beta receptors are blocked may cause breathing problems or asphyxation (oxygen deprivation/death)

Question 12

Give an example of an appropriate BB for asthmatic patients with CV problems

Answer 12

Atenolol (treats high BP and cardiac arrthymias) - mainly has beta 1 receptor blocking activity - little effect on respiratory blocking (beta 2 receptors)

Question 13

How does exercise affect BB action?

Answer 13

Exercise and BB have opposing effects
- exercise doesn’t override the reduction of HR due to the drugs
may seriously alter serum lipid levels depending on type of BB

Question 14

How does BB effect cardiac output?

Answer 14

BB target HR and SV therefore CO is much lower

- decreased resting and exercising HR - effect exercise capacity

Question 15

During exercise what methods should be employed to calculate intensity?

Answer 15

RPE

Question 16

What happens to RHR, ex HR, CO and VO2 max with the use of BB?

Answer 16

RHR - decreases by all types of BB
exercising HR - decreased by all types
CO - conflicting data - exercise either reduces CO or doesn’t change it
VO2 max - reduced acutely by all types, can increase with training with chronic use

Question 17

What are the metabolic consequences of BB?

- lipolysis, muscle TGs utilisation, glycogenolysis, serum K+ levels

Answer 17

AT lipolysis is impaired
Muscle TG utilisation - impaired by non selective agents
Glycogenolysis - impaired by non selective
Serum K+ - post exercise levels are decreased with non selective agents

Question 18

How do BB impact on exercise performance and training?

Answer 18

Cardioselective (atenolol) suppresses MHR less than noncardioselective agents
- all BB reduce VO2 max
Non selective - can suppress training effects acutely but chronic use -fitness improvements with exercise
Decreased time to exhaustion - tire more quickly
Cardioselective - interfere with substrate use less than non selective during exercise

Question 19

Benefits of BB in sports (however known as abusing BB)

Answer 19

Slower HR in shooting = reduced DM tremor
Pistol shooting performance increases by 13.4% mainly from reduced hand tremor not HR
No effects on visual, auditory, reaction time, strength, power or muscle endurance

Question 20

What is propanolol’s effect on sweating?

Answer 20

Can increase sweat loss which means fluid replacements necessary but need to be careful in HT patients who need to avoid excess salt as sodium will need to be replaced

Question 21

Basic guidance and tips for BB use

Answer 21

Adjust exercise targets as RHR and exercising HR are affected
No appearance of thermoregulatory effect but propanolol can increase sweat loss so fluid replacement with Na+ is unwise in HT patients who have to avoid salt
It is banned in competition unless verified
Cardioselective (atenolol) are better than non selective (propanolol)
Monitor dose and effect as fitness improves
Careful combining BB and exercise - ex has multiple benefits