Intravesical ions, osmolality and pH influence the volume pressure response in the normal rat bladder, and this is more pronounced after DMSO exposure.

The influence of intravesical ions, osmolality, pH value, and active transurothelial NaCl-transport inhibition (furosemide) on the rat bladder volume-pressure response was studied according to the concept of a permeable urothelium and according to direct effects of osmolality and K+ on in vitro muscle preparations. It was found that the bladder capacity was decreased by K+, hyperosmolality and pH5, whereas it was increased by hypoosmolality, electrolyte-free media, furosemide and pH 8. The effects were found to be pronounced after dimethyl sulfoxide (DMSO) exposure. In this condition, furosemide showed less effect. It has been suggested that, especially in diseased bladders with increased permeability, frequent voiding and painful urge sensations are due to an enhanced urine access to nerve and muscle cells of the detrusor. On the other hand, frequent voiding reduces the urinary contact time within the bladder, thereby protecting from urine recirculation and thus from renal insufficiency. It has been further suggested that the bladder is not exclusively under central nervous control. As far as the present study is concerned, CO2, water, and normal saline do not seem to be appropriate urodynamic test media for providing the standard situation of bladder filling.