Effects of Acetylcholine (ACh alone)

Stimulation of parasympathetic nerve fibres can be mimicked by adding a few drops of Ringer's solution containing acetylcholine (10 µg/ml) to the frog heart in the region of the sinus venosus.

The following trace shows a normal heart beat followed by a trace recorded after dropwise application of acetylcholine.

Task
You should

1. measure the rate of contraction, and
2. observe changes in the force of both atrial and ventricular contraction, before and after application of acetylcholine, until peak effects are observed.

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