Urol Res (2007) 35:243–246 DOI 10.1007/s00240-007-0107-3 123 ORIGINAL PAPER The eVect of traditional risk factors for stone disease on calcium oxalate crystal adherence in the rat bladder Charles L. Smith · John V. St Peter Received: 22 February 2007 / Accepted: 12 July 2007 / Published online: 1 August 2007  Springer-Verlag 2007 Abstract Crystal adherence in the urinary tract has been studied using the chemically injured rat bladder and cell cultures. These studies have provided evidence that mucin prevents adherence and have studied various compounds for their ability to promote or inhibit crystal adherence. Lit- tle work has been done examining the eVect on crystal adherence of traditional risk factors for stone disease. The study reported here examined the eVect hypercalciuria, hyperoxaluria and pH on calcium oxalate crystal adherence using the intact rat bladder model. Calcium at levels seen in hypercalciuric stone formers was associated with increased adherence. Oxalate at levels seen in stone formers had no eVect on adherence. There was a tendency to increased crystal adherence at higher pH values only when phospho- rus was present as the buVer. Hypercalciuria is a risk factor for stone disease by increasing the level of saturation of cal- cium oxalate and calcium phosphate in the urine and by decreasing inhibitor function. This study suggests that it may also play a role by increasing crystal adherence within the urinary tract. Keywords Calcium oxalate · Crystal adherence · Mucin · Hypercalciuria · Hyperoxaluria Introduction Crystal adherence within the urinary tract is considered a necessary step in urolithiasis. To gain insight into the mechanism of adherence in the urinary tract, studies have been done in the bladder of intact animals [1, 2]. These studies chemically damaged the bladder and tested sub- stances for their ability to restore resistance to crystal adherence. Although these studies provide insight into a role for mucin to prevent crystal adherence and allow examination of promoters and inhibitors of crystal adher- ence, they do not explain why crystals adhere in stone patients. In the study reported here, we examined the poten- tial role of three traditional risk factors for stone disease to promote crystal adherence in the intact rat bladder. Hypercalciuria increases the saturation of the urine for calcium oxalate and calcium phosphate and reduces the inhibitory activity of the urine for calcium oxalate precipi- tation [3]. Hyperoxaluria increases urinary saturation for calcium oxalate. Urine pH promotes uric acid precipitation in the acid range and calcium phosphate precipitation in the alkaline range. These abnormalities are common in stone formers but their eVect on crystal adherence has received little attention. Materials and methods Animal preparation was similar to a previous study examin- ing the role of mucin to prevent crystal adherence [1]. Female Sprague–Dawley rats (225–250 g) were anesthe- tized with intraperitoneal sodium pentobarbital (40 mg/kg), the abdominal cavity opened and the ureters ligated to prevent urine from entering the bladder. The bladder was catherized with silicone tubing to a standard length and a C. L. Smith (&) Division of Nephrology, Hennepin County Medical Center, University of Minnesota, Minneapolis, MN 55415, USA e-mail: smith156@umn.edu J. V. St Peter Experimental and Clinical Pharmacology, College of Pharmacy, Division of Endocrinology, Hennepin County Medical Center, University of Minnesota, Minneapolis, MN 55415, USA