Prodromal contractions and contractility in the feline bladder.

In the cat there are at least two distinct contractile states of the bladder during urine storage, one when prodromal contractions are present and one when non-micturating contractions are present. It is proposed that prodromal contractions are myogenic. This proposition was examined by comparing prodromal contractions before and after hypogastric nerve section as well as comparing prodromal contractions with the contractions that remain after sectioning of the hypogastric nerves. Key contraction characteristics, such as amplitude, maximum gradient and the variance of the intercontraction interval were not significantly changed by hypogastric nerve section, providing volume effects were corrected for, which suggested that prodromal contractions have a myogenic origin.