Practical pharmacology. Part 5. Dose response curve of acetylcholine презентация

Dose response curve of acetylcholine
In the presence of atropine

Atropine is a competitive antagonist for Ach on muscarinic receptors (M) of the isolated rabbit jejunum.
Higher concentrations of Ach are needed to displace atropine from M receptors and eliciting a response.
PRINCIPLE :

Rabbit intestine
Tyrode‘s solution
Temperature 37˚C
Aeration by air pump
OUR ISOLATED ORGAN

0.1 ml

0.2 ml

0.3 ml

0.4 ml

0.1 ml
atropine

0.1 ml
atropine

0.2 ml
Ach.

0.4 ml
Ach.

0.6 ml
Ach.

0.8 ml
Ach.

1 ml
Ach.

Now we need to draw the dose response curve

0.1 ml
0.2 ml
0.3 ml
0.4 ml
0.2 ml
0.4 ml
0.6 ml
0.8 ml
1 ml
Ach. only
Ach. +
atropine

convert volumes into doses
0.1 g%
0.1 g
100 ml
x
0.1 ml

x
=
100
0.1 x 0.1
=
0.0001 g
=
0.1 mg

Now draw your curve

Dose (mg)
Response (cm)
Ach.
Ach.+atropine

Conclusion

Atropine is a reversible competitive muscarinic
receptor antagonist causing parallel rightward
shift of dose response curve of acetylcholine
Atropine decrease potency of acetylcholine
and not affect efficacy

Notes

Do not forget your tools

Complete your book