METHODS: Totally 63 female Sprague-Dawley rats were used. They were divided into two groups; BOO and sham operated (SHAM) groups. BOO was created by a partial ligation of the urethra with a nylon suture, whereas SHAM group of rats underwent only exposure of the urethra without ligation. Six weeks after surgery, three experiments were performed: 1) mRNA expression of N-Ca in the bladder, 2) in vitro functional studies of detrusor strips focusing on the effects of -cono- toxin GVIA (CTX; a selevctive N-Ca inhibitor, 10 -6 M) on carbachol (CCh)-induced and electrical field stimulation (EFS)-induced contrac- tions, and 3) cystometric investiogations (CMG) with continuous saline- instillation in a conscious state with intravenous administration of CTX (3 g/kg). RESULTS: N-Ca mRNA expression in the detrusor was about 50 times higher in BOO than SHAM group. CTX did not suppress CCh-induced contractions in either group. The EFS-induced contrac- tions were weaker in the detrusor of BOO than SHAM group. CTX significantly suppressed the EFS-induced contractions in BOO group, but not in SHAM group (Figure 1 A, B). The suppressive effect of CTX on the EFS-induced contractions was more pronounced in the cholin- ergic component at 10 Hz. In CMG, the number of non-voiding con- tractions (NVCs) was significantly greater in BOO group than SHAM group. The number of NVCs was significantly decreased after CTX- administration in BOO rats (Figure 1 C). CONCLUSIONS: The results of the current study suggest that N-Ca may have an important role in facilitating release of excitatory transmitters including ACh from the efferent nerve terminals innervating the detrusor of the BOO rats, and this may link to the development of detrusor overactivity associated with BOO. Source of Funding: None 38 MOUSE VOIDING PATTERNS ARE STRAIN-SPECIFIC: A NOVEL ASSAY FOR AGE-RELATED DEVELOPMENT OF LOWER URINARY TRACT SYMPTOMS (LUTS) Weiqun Yu, Warren Hill, John Larigakis, Boston, MA; Cheryl Ackert-Bicknell, David Harrison, Gary Churchill, Bar Harbor, ME; Mark Zeidel*, Boston, MA INTRODUCTION AND OBJECTIVES: LUTS afflicts millions of people, particularly the elderly, and engenders enormous medical costs. To develop a mouse model of LUTS in aging that will permit detection of genetic predisposition in mouse populations, we developed an assay of voiding dysfunction. We used this assay to examine the phenotypic reproducibility of voiding among 8 genetically diverse strains of mice. If urine localization patterns are a heritable character- istic we can use systems genetics to conduct genome wide association studies to identify quantitative trait loci (QTL) and novel genes linked to development of age-related LUTS. METHODS: The 8 founder strains of the Collaborative Cross (a large panel of multi parental recombinant inbred mouse lines) were examined. Four mice of each strain were placed individually in cages on filter paper for 4 h. Urine spots were visualized with UV light, photographed and images analyzed. Mice were assayed on 5 consec- utive days in the morning, afternoon and at night (7pm-11pm). Param- eters quantified included: spot #, % vol (Vol) in the largest void spot, % Vol in corners (comprising 20% of surface area (SA)), % Vol in center (40% of SA) and total urine Vol. RESULTS: Voiding parameters within strains showed no day effects or mouse effects over 5d, indicating that strains had consistent voiding patterns and that voiding did not change with acclimation. Testing for strain effects by ANOVA revealed significant differences for all parameters tested (urine spot number, P = 0.03; % in largest void spot, P = 0.004; total urine Vol, P = 0.002; %corner localization, P = 0.0003; %center localization, P  0.0001). Averaged over all time periods, urine spot numbers ranged from 5  1 for WSB/EiJ mice to 29  12 for PWK/PhJ mice; %Vol in largest void spot ranged from 26  2% for CAST/EiJ mice to 73  16% for 129S1/SvImJ mice; and %Vol in corners ranged from 22 4% for NZO/HilLtJ mice to 62  13% for 129S1/SvImJ mice. There were significant time of day effects for several parameters indicating that micturition behavior changes diur- nally. We are now performing cystometrograms to correlate voiding patterns with bladder urodynamics. CONCLUSIONS: Rigorous characterization of this assay dem- onstrates that murine voiding behavior is highly reproducible and strain specific thus indicating it is a heritable phenotype. We are now begin- ning longitudinal studies of age-related changes in urinary tract function to identify genes which may relate to the development of LUTS in aging. Source of Funding: Supported by grant DK097818 from the National Institute of Diabetes and Digestive and Kidney Diseases to Mark Zeidel 39 UPREGULATION OF P2X PURINERGIC RECEPTORS IN BLADDER OXIDATIVE STRESS AUGMENTS SMOOTH MUSCLE CONTRACTIONS Qi Zhang, Mike Siroky, Kazem Azadzoi*, Boston, MA INTRODUCTION AND OBJECTIVES: Neural regulation of bladder contraction involves both cholinergic and nonadrenergic, non- cholinergic (NANC) mechanisms. Nerve stimulated bladder contrac- tions appear to involve acetylcholine and ATP co-released from para- sympathetic nerve terminals. Our goal was to examine P2X purinergic receptors expression and their role in increased smooth muscle con- tractions after bladder exposure to oxidative stress conditions. METHODS: Confluent cultured human bladder smooth muscle cells (BSMC) were incubated under normoxia (21% oxygen, 5 dishes) and continuous hypoxia (2% oxygen, 5 dishes) conditions for 48 hours using a computerized cell oxycycler system. To study oxidative stress, another five dishes of cells were incubated under cyclical hypoxia/ reoxygenation using 2% oxygen for 30 minutes followed by reoxygen- ation with 21% oxygen for one hour; cycling in this manner for 48 hours. Bladder oxidative stress was produced in rabbits by inducing arterial atherosclerosis and chronic bladder ischemia. Human BSMC samples and tissues from eight weeks ischemic rabbit bladders (n=8) and age-matched controls (n=8) were processed for ELISA of oxidative stress markers, western blotting of P2X purinergic receptors and meas- urement of contractile responses to electrical field stimulation (EFS) at 10 volts and varying frequencies in the organ bath. RESULTS: P2X1 and P2X2 purinergic receptors were ex- pressed in human BSMC while P2X1, P2X2, P2X3, P2X4, P2X5 and P2X7 were found in the rabbit bladder tissues. Continuous exposure of human BSMC to hypoxia downregulated both P2X1 and P2X2 expres- sion. Oxidative stress significantly decreased P2X1 and increased P2X2 expression in human BSMC. Accumulation of oxidative radicals in the rabbit ischemic bladders were associated with upregulation of Vol. 189, No. 4S, Supplement, Saturday, May 4, 2013 THE JOURNAL OF UROLOGY e15