EVIDENCE FOR PURINERGIC NEUROTRANSMISSION IN HUMAN URINARY-BLADDER AFFECTED BY INTERSTITIAL CYSTITIS

Detrusor specimens were obtained from 5 patients affected by interstit ial cystitis (IC) and 5 patients with bladder carcinoma (controls). Mu scle strips were prepared for in vitro pharmacological studies. In all detrusor strips taken from IC patients, an important portion of the e lectrically-induced contraction was atropine-resistant. In contrast, a tropine-resistance was never observed in control detrusors. H-1 and H- 2, antagonists did not affect noncholinergic contractile response whic h, conversely, was abolished following desensitization to alpha,beta m ethylene ATP (APCPP). Detrusor muscle from patients affected by IC exh ibited an increase in sensitivity to APCPP and a decrease in sensitivi ty to acetylcholine with respect to control detrusor. Taken together t hese results are consistent with the presence of a purinergic neurotra nsmission in parasympathetic nerve terminals of the urinary bladder af fected by IC, probably as a consequence of alterations in the innervat ion and/or electrical coupling between smooth muscle cells. The sensit ivity of IC detrusor muscle to histamine was much lower than that of c ontrol detrusor, suggesting a desensitization of histamine receptors p resent in the bladder wall of IC patients.