Altered bladder function in elastin-deficient mice at baseline and in response to partial bladder outlet obstruction

OBJECTIVE To examine functional and molecular changes of the bladders from elastin-haploinsufficient mice (Eln(+/-)) at baseline as well as in response to partial bladder outlet obstruction (pBOO). MATERIALS AND METHODS Female Eln(+/-) and wild type (Wt) mice (3-4 months old) were studied. The bladder elastin content was quantified by measuring desmosine. Mice were divided into two groups to undergo surgery to create pBOO or to undergo sham surgery. Three days after surgery, bladder function was evaluated by in vivo cystometry, and the contractile response of bladder strips exposed to electrical field stimulation (EFS) and carbachol was examined by ex vivo myography. RESULTS The Eln(+/-)-sham mice had a 33.6% decrease in bladder elastin compared with Wt-sham mice. Cystometry showed significantly decreased bladder compliance and capacity in Eln(+/-)-sham vs Wt-sham mice; pBOO increased bladder compliance and capacity to a greater extent in Eln(+/-) mice compared with Wt mice. Bladder strips from Eln(+/-)sham mice showed a significantly heightened contractile response to both EFS and carbachol compared with Wt-sham mice. A significantly increased contractile response to carbachol was detected in Wt-pBOO vs Wt-sham but not between Eln(+/-)-pBOO and Eln(+/-)-sham mice. CONCLUSION The results that elastin-deficient mice had decreased bladder compliance and capacity and increased bladder contractility; and that Wt-pBOO mice showed an enhanced contractile response to carbachol, but Eln(+/-)-pBOO mice did not, suggest that elastin is critical for normal bladder function and is involved in bladder response to pBOO.