Effects of Acetylcholine + Physostigmine

Physostigmine (eserine) inhibits acetylcholinesterase, the enzyme responsible for terminating the action of acetylcholine at the receptor site.

Physostigmine (100 µg/ml) should have little effect on the heart, although minor effects are often seen. The control trace is taken as that after application of physostigmine.

Task
You should measure changes in the heart rate, and observe effects on the force of contraction, before and after application of acetylcholine (10 µg/ml) against a background of physostigmine. The results from these traces should also be compared to those of acetylcholine alone.

Use the play/pause button to halt the display to enable you to take your measurements more easily.