Effects of substances that act as stimulants including caffeine, amphetamines and beta agonists on exercise training and performance
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Ephedrine - effects
• Increases heart rate, cardiac output, blood pressure • Bronchodilation • Hypertension, insomnia, irritability • Increases anaerobic power output, endurance • Possibly heart attack, stroke, death • Pseudoephedrine (form of ephedrine) – found in cold and flu remedies, can lead to a positive doping test
what kind of neuron is ephedrine
Noradrenergic neuron
Where are some receptors available for ephedrine
pre-synaptic nerve ending
Where do adrenaline and noradrenaline have receptors
in the cell membrane
What happens when alpha 2 receptors are on the pre-synaptic nerve ending
They act as negative feedback and stops to release of more noradrenaline
How does the body control effects of neurotransmitters
• Tissue-specific location of receptor subtypes – heart, liver, skeletal muscle etc. • Receptor specific affinity of neurotransmitters • Rapid uptake and metabolism of neurotransmitters • Alterations in receptor number in certain situations
What is the on switch
The action potential and the release of noradrenaline
What is the off switch
the removal of neurotransmitters from the synaptic cleft so its not binding to the receptors and also negative feedback
Epinephrine/norepinephrine - alpha 1 receptor
smooth muscle contraction
Epinephrine/norepinephrine - Alpha 2 receptor
Smooth muscle contraction inhibition of neurotransmitter release
Epinephrine/norepinephrine - Beta 1 receptor
heart muscle contraction
Epinephrine/norepinephrine - Beta 2 receptor
Smooth muscle relaxation
What are drugs called which activates a receptor
agonists
Which drugs are agonists
• Epinephrine - norepinephrine
Antagonist
A drug which blocks a receptor
What drug is ephedrine similar to
Adrenaline
What does ephedrine do
it binds to the uptake mechanism, and blocks the receptor, meaning that epinephrine and norepinephrine cant be reuptaken
what happens when neurotransmitters cant be reuptakeb
they keep activating the receptor
Endogenous structures
• Noradrenalin • Adrenaline • Dopamine • Isoprenaline
Clinical use of Adrenoceptor agonists
• Anaphylactic shock (Epinephrine) • Cardiac Arrest (Epinephrine) • Asthma (b2) • Decongestant (b2)
Most common asthma treatment
• Salbutamol
Asthma &b2-agonist
• Activates the beta-2 receptors in the airways • Might have some effect on beta-1 at high doses • Relaxes the smooth muscle here, thus widening the airways and allowing better airflow. Some have suggested that athletes could abuse these to maximise respiratory function
Bronchodilators (Beta-2 agonists)
• Asthma or exercise-induced bronchoconstriction often occur because airways becomes too dry or cold, are exposed to allergens or pollutants • Beta-2 agents are the main way of treating it • These dilute the airways • Since specifically bind to beta 2 receptors, tend to have a few side-effects
Effect of bronchodilators on exercise performance
• Most studies have shown that, with inhaled bronchodilators like beta 2 agonists, the dose is too low to have any real ergogenic effect • However, oral bronchodilators given a high systemic dose which can increase muscle strength