Pre-Lab Lecture Flashcards
What hormone do muscarinic receptors respond to?
Acetylchloine
What are muscarinic receptors?
Histamine receptors
What physiological solution is used in an organ bath?
Krebs Tyrode Solution
Why is Kerbs Tyrode Solution used?
Because it contains lots of ions among them are the calcium ions which cause contraction
The organ bath is kept in a water jacket. To what degree is this heated?
37 degrees
A thread is threaded through the gut to sense contraction; what piece of apparatus is this attached to?
A transducer
What does a transducer do?
Measures the amount of pull on the thread and turns into into a signal which is displayed on a computer
The display produces a peak if the muscle has contracted; what causes the rise of the peak and what causes the fall?
The drug being added causes the rise and the drug being washed out causes the fall
In order to work out the concentration of acetylchlone in the organ bath what three pieces of information do you need?
The total volume in the organ bath
The concentration of acetylchlone added
The dose (volume) of acetylcholine added
What is the EC50?
The concentration of a drug/agonist required to produce half the maximum response
What is the definition of a full agonist?
An agonist that binds to a receptor and activates it to produce full efficacy at that receptor
What is the definition of a partial agonist?
An agonist that binds to a receptor but only has partial efficacy even if all the receptors are occupied - the maximum response is less than that we know the tissue can produce
How does a reversible antagonist bind to a receptor?
With weak non-covalent interactions such as hydrogen bonds, electrostatic interactions etc.
How does an irreversible antagonist bind to a receptor?
With strong covalent bonds
How would you overcome the effects of a reversible antagonist?
Increasing the concentration of the agonist means there is more chance the receptor qill bind ith an agonist rather than the antagonist
What is the EC50?
The MOLAR concentration of a drug/agonist required to produce half the maximum response
How would you overcome the effects of a reversible antagonist?
Increasing the concentration of the agonist means there is more chance the receptor will bind with an agonist rather than the antagonist
How would you overcome the effects of an irreversible antagonist?
You cant - increasing the concentration of agonist will not affect it and neither will washing it out
What is meant by a competive antagonist?
One who competes for the same binding site as the agonist
What does the dose of a drug refer to?
The volume added
What does a concentration response curve show?
The relationship between the log of the concentration of an agonist and the response produced
What is the potency of a drug?
A measure of the concentration of a drug at which its effective/what concentration of a drug is required to give a certain response
What is the affinity of a drug?
The strength of interaction between the ligand and the receptor
If you had a drug with a high potency would you expect the EC50 to be low or high and why?
The higher the potency = the lower the EC50 because the higher the potency means the less concentration you need to get a particular response so therefore the concentration you need to get a half response (EC50) will be lower
What is the efficacy?
How good is the drug-receptor complex is at stimulating the response
If a drug has no efficacy what is it?
An antagonist - blocks the receptor from producing a response
In order to plot the concentration-response curve you must convert the molar concentration into log. How is this done?
Log (concentration)
How would you convert the log of a concentration back into the molar concentration?
Inverse log (log concentration)
