Activation of the kallikrein kinin system in interstitial cystitis

Purpose: We investigated whether the kallikrein kinin system is activated i n interstitial cystitis by measuring urinary excretion rates of kinin pepti des, active and total kallikrein, and the kininase neutral endopeptidase in women with interstitial cystitis. We compared these excretion rates to a c ontrol group of women with stress incontinence and normal bladder function. Materials and Methods: Catheter urine was collected from subjects during a water diuresis (approximately 10 mi. per minute) before and after distentio n of the bladder with 100 mi. water. The contribution of the bladder wall t o urinary kinins was assessed by measuring the change in kinin levels after 2 minutes of bladder stasis before and after distention. Results: Absolute bradykinin and kallidin excretion rates were similar in w omen with interstitial cystitis and control subjects. Two minutes of bladde r stasis after bladder distention increased urinary bradykinin (p = 0.02) b ut not kallidin excretion rates. Active and total kallikrein excretion rate s were similar in patients with interstitial cystitis and control subjects. Neutral endopeptidase excretion rates were reduced in the initial urine co llection from subjects with interstitial cystitis but were similar in both groups during later collection periods. Conclusions: These data provide evidence for increased bradykinin levels in the bladder wall of subjects with interstitial cystitis, which may be due in part to reduced neutral endopeptidase levels. These increased bradykinin levels may participate in the pathogenesis and symptomatology of interstit ial cystitis.