Urodynamic Events: Introduction
In order to observe the urodynamic events in the renal pelvis, we have used the hamster. The single, rather long papilla of the hamster lies within the pelvis under several layers of fat and connective tissue.   After careful removal of this covering, the muscular contractions of the peripelvic wall become visible.  A fiberoptic light is placed beneath the pelvis, transilluminating the papilla within it.

Fiberoptic Illumination
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The peristalsis of the papilla has a profound effect on the papilla.  In the hamster, the rate of peristalsis is normally 20 to 30 per minute. Other mammals have different rates, some faster, others slower. As the wall contracts, the papilla narrows. Its diameter is reduced by as much as 20%. This means a reduction of 36% of the cross sectional area. At the moment the peristaltic wave has moved down over the tip of the papilla, the papilla moves upward. The average movement is about 300 m . The peristaltic contractions are controlled by a pacemaker situated in the uppermost parts of the pelvis. Sections of the pelvic wall have their own intrinsic peristaltic rhythm which is slower than that of the pacemaker. Thus there is coupling taking place as the rhythms of the sections are driven by the pacemaker. It should be emphasized that the movement of the papilla is strictly driven by the pelvic wall. The renal papilla has no smooth muscle, and therefore no intrinsic contraction.

Peristalsis
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