Summary
Clot retraction was studied by setting up ribbon-shaped clots in a pharmacological
bath and recording the progress of contraction on a kymograph. Drugs could be added
to the bath or washed out at any stage. Papaverine, theophylline and cytochalasin
B each reversed the upward course of the kymograph tracing ; contraction began again
when the drugs were washed from the bath. This phenomenon resembles the behaviour
of smooth muscle under similar circumstances.
