The effect of furosemide-induced diuresis on rabbit micturition and bladder contractile function.

The morphology and contractile function of the urinary bladder can be significantly altered in response to specific forms of physiological and pathophysiological stress placed upon it. For example, partial outlet obstruction results in a marked increase in bladder mass (weight) with associated alterations in the contractile response to specific forms of stimulation. Diabetes and its associated diuresis also induce significant alterations in bladder weight and contractile function. The current study was designed to determine if the increase in bladder weight induced by diuresis is associated with contractile alterations similar to those observed following partial outlet obstruction. Diuresis was induced by continual slow-infusion of furosemide using osmotic pumps. The results can be summarized as follows: 1) After two weeks of furosemide treatment the bladder mass was significantly greater than in the controls. 2) Furosemide-treated rabbits consumed and excreted three times more fluid than did the controls. 3) In vivo cystometric capacity and bladder compliance of the furosemide-treated rabbits were significantly increased. 4) Diuresis induced a significant increase in the contractile response of isolated bladder body strips to field stimulation, ATP, bethanechol, and KCl. 5) Furosemide treatment had no effects on the contractile responses of bladder base strips to any form of stimulation. Diuresis resulted in a significant increase in bladder weight and an associated increase in the contractile state of the bladder body, presumably through an increase in smooth muscle.