Effects of Acetylcholine (ACh + Atropine)

The effects of acetylcholine can be further investigated by examining the action of other agents, which affect neurotransmission at cholinergic synapses. Atropine blocks muscarinic acetylcholine receptors on cardiac muscle cells. Atropine alone should have little effect on the denervated heart.
However, in most experiments atropine does have a small effect on heart rate. In the following experiment, the control trace is taken as that after application of atropine (5 µg/ml) alone. The point of application of acetylcholine (10 µg/ml) is marked.

Task
You should measure heart rate, and observe changes in the force of contraction, before and after application of acetylcholine. 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.