Age-dependence of the spontaneous activity of the rat urinary bladder.

Abnormal mechanical function of the bladder is manifested in a number of ways including higher frequency of involuntary detrusor contractions associated with reduced compliance of the bladder that is responsible for an increase in intraluminal pressure during filling. There are basically two ways to approach experimentally these problems: (1) by studying the neural control of the lower urinary tract function, and (2) by measuring the properties of smooth muscle cells in the bladder wall. Studies on smooth muscle function often do not take the origin of smooth muscle cells into account i.

Developmental changes in spontaneous smooth muscle activity in the neonatal rat urinary bladder.

Changes in spontaneous activity of the urinary bladder during postnatal development were examined in muscle strips from the base and dome of bladders from 1- to 5-wk-old rats. Activity was analyzed using fast Fourier transformation (FFT), nonlinear cross prediction, and the Shannon entropy test. Spontaneous activity was not detected in strips from 1- to 5-day-old rats but was observed in 50% of strips from 6- to 7-day-old rats and was prominent in strips from 2-wk-old animals.

Effect of cryoinjury on the contractile parameters of bladder strips: a model of impaired detrusor contractility.

In anesthetized Sprague-Dawley rats, the bladder was exposed and cryoinjury was induced by abruptly freezing the serosal side of the bladder wall with a chilled aluminum rod previously placed on dry ice (-40 degrees C). Five days later, the rats were euthanized, and strips were prepared from the area adjacent to the injury. Neurally and alpha,beta methylene-ATP (alpha,beta m-ATP; 50 microM)-evoked contractions were measured in bladder strips from cryoinjured or intact bladders prepared from sham-operated rats.