Bladder urothelial cells from patients with interstitial cystitis have an increased sensitivity to carbachol.
OBJECTIVE
The presence of muscarinic receptors on bladder urothelial cells (BUC), suggests BUC may be a target for antimuscarinics. This study determined whether human BUC are responsive to a muscarinic agonist and if so, whether responses are altered in interstitial cystitis (IC) BUC.


METHODS
Primary urothelial cell cultures were established from cystoscopic biopsies. Normal (NB) and IC BUC were studied using calcium imaging techniques as a means to monitor the response to muscarinic receptor activation with the agonist, carbachol (CCh). Changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured with fura-2 ratiometric microfluorimetry. Dose-response curves (CCh dose vs. [Ca(2+)](i)) were measured in IC and NB BUC. Tolterodine was used to confirm the specificity (muscarinic versus nicotinic) of CCh evoked increases in [Ca(2+)](i).


RESULTS
CCh induced a dose-dependent increase in [Ca(2+)](i). Potency and efficacy of CCh was significantly greater in IC BUC. The maximal increase in [Ca(2+)](i) was 136.3 +/- 5.1% over baseline in 78 cells from 4 IC patients versus 92.4 +/- 4.8% over baseline in 67 cells from 4 NB subjects (P < 0.01). The EC50 of the evoked increase was 1.10 +/- 0.14 microM versus 3.36 +/- 0.72 microM (P < 0.01) in BUC from IC and NB controls, respectively. Removal of extracellular calcium or application of tolterodine, abolished CCh evoked increase in [Ca(2+)](i) in IC and NB BUC.


CONCLUSIONS
The greater sensitivity of IC BUC to CCh suggests that IC patholobiology may also include alterations muscarinic signaling. The physiologic sequelae of muscarinic activation in BUC need to be further investigated.
Gupta
Gopal N
GN
Division of Urology, Department of Surgery, University of Maryland School of Medicine, Baltimore, USA.
Lu
Shao-Gang
SG
Gold
Michael S
MS
Chai
Toby C
TC
D000328:Adult; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology*; D002478:Cells, Cultured; D018679:Cholinergic Agonists / Q000494:pharmacology*; D018856:Cystitis, Interstitial / Q000473:pathology*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D001743:Urinary Bladder / Q000473:pathology*; D019459:Urothelium / Q000473:pathology
D018679:Cholinergic Agonists; D002217:Carbachol; D002118:Calcium