Preliminary observations on the mechanical and electrical activity of the rat ureter.

1. The electrical and mechanical activity have been recorded from the rat ureter in situ.2. The frequency of peristaltic contractions is usually about 25/min, and each peristalsis is preceded by electrical activity which normally travels from the renal end of the ureter towards the vesicular end. The electrical and mechanical activities are closely correlated.3. The velocity of propagation of the electrical activity is about 20 mm/sec.4. The normal electromyogram probably arises in the first 5 mm of the renal end of the ureter, and retrograde activity may arise from a similar region at the vesicular end of the ureter.5. A close arterial injection technique shows that the proximal end of the ureter behaves as if it possessed alpha-receptors; the distal end behaves as if it had beta-receptors. This conclusion is discussed.