[Adult Male Ureterocele Detected by Urinary Frequency].

A 27-year-old Japanese man visited our urological department due to urinary frequency, and we detected a ureterocele by cystoscopy. The treatment consisted of an endoscopic-laser incision of the ureterocele. After the operation, the patient's symptoms subsided, and the vesicoureteral reflux and urinary infection disappeared. With the advances in image diagnostic technology, a ureterocele is easily diagnosed during childhood. In the present case, the ureterocele may have increased in volume over a period of decades, causing the urinary frequency. An endoscopic incision is the standard treatment for ureterocele, but there are concerns about vesicoureteric reflux after the endoscopic-laser incision, the patient is still doing well. The present case indicates that endoscopic-laser incision is an effective treatment for a ureterocele, at least in adult patients.

Arterial Transit Time-corrected Renal Blood Flow Measurement with Pulsed Continuous Arterial Spin Labeling MR Imaging.

PURPOSE: The importance of arterial transit time (ATT) correction for arterial spin labeling MRI has been well debated in neuroimaging, but it has not been well evaluated in renal imaging. The purpose of this study was to evaluate the feasibility of pulsed continuous arterial spin labeling (pcASL) MRI with multiple post-labeling delay (PLD) acquisition for measuring ATT-corrected renal blood flow (ATC-RBF). MATERIALS AND METHODS: A total of 14 volunteers were categorized into younger (n = 8; mean age, 27.0 years) and older groups (n = 6; 64.8 years). Images of pcASL were obtained at three different PLDs (0.5, 1.0, and 1.5 s), and ATC-RBF and ATT were calculated using a single-compartment model. To validate ATC-RBF, a comparative study of effective renal plasma flow (ERPF) measured by 99mTc-MAG3 scintigraphy was performed. ATC-RBF was corrected by kidney volume (ATC-cRBF) for comparison with ERPF. RESULTS: The younger group showed significantly higher ATC-RBF (157.68 ± 38.37 mL/min/100 g) and shorter ATT (961.33 ± 260.87 ms) than the older group (117.42 ± 24.03 mL/min/100 g and 1227.94 ± 226.51 ms, respectively; P < 0.05). A significant correlation was evident between ATC-cRBF and ERPF (P < 0.05, r = 0.47). With suboptimal single PLD (1.5 s) settings, there was no significant correlation between ERPF and kidney volume-corrected RBF calculated from single PLD data. CONCLUSION: Calculation of ATT and ATC-RBF by pcASL with multiple PLD was feasible in healthy volunteers, and differences in ATT and ATC-RBF were seen between the younger and older groups. Although ATT correction by multiple PLD acquisitions may not always be necessary for RBF quantification in the healthy subjects, the effect of ATT should be taken into account in renal ASL-MRI as debated in brain imaging.

[A case of metachronal testicular tumor eight years after medical treatment of extragonadal germ cell tumor].

A 22-year-old man was admitted to our hospital complaining of a left cervical mass. Computed tomography (CT) showed multiple enlarged lymph nodes at the left cervical vein and para-aortic areas. Histological examination of a biopsy indicated an embryonal carcinoma. The levels of human ß-chorionic gonadotropin (ß-HCG) and lactic dehydrogenase (LDH) were both elevated. Ultrasonography revealed testicular calcification, but there were no findings on magnetic resonance imaging (MRI). The patient was diagnosed as having an extragonadal germ cell tumor. After four courses of chemotherapy with BEP protocol (bleomycin, etoposide and cisplatin), retroperineal lymph node dissection (RPLND) was performed and there was no involvement of the viable cells in the resected lymph nodes. Eight years after chemotherapy, he noticed an enlargement of his left scrotum without pain. ß-HCG was again elevated. A unilateral high orchiectomy was performed, and histology revealed a seminoma. He was staged as pT1N0M0S0. Six months later he remains disease-free.

Alpha 1-adrenoceptor blocker may improve not only voiding but also storage lower urinary tract symptoms caused by (125) I brachytherapy for prostate cancer.

Purpose. To assess changes in lower urinary tract symptoms (LUTS) within 1 year after brachytherapy in patients receiving alpha 1-adrenoceptor antagonists. Methods. We retrospectively evaluated 116 patients who underwent (125)I prostate brachytherapy in our institute. Seventy-one patients were treated with a combination of external beam radiation therapy and brachytherapy. Alpha 1-adrenoceptor antagonists were prescribed to all patients after brachytherapy. International Prostate Symptom Score (IPSS) forms and postvoid residual urine volume were recorded at all follow-up visits. Results. Forty-nine patients were given tamsulosin hydrochloride, 32 were given silodosin hydrochloride, and 35 were given naftopidil for up to 6 months after seed implantation. Patients given tamsulosin or naftopidil tended to show a higher peak IPSS and slower recovery to baseline values than those given silodosin. The patients given naftopidil showed an insufficient recovery in storage symptoms in naftopidil group in comparison with tamsulosin group at 3 months and with silodosin group at 6 and 9 months. Conclusions. In the management of LUT after brachytherapy, silodosin may provide a more favorable improvement. Silodosin and tamsulosin may have an advantage in improving not only voiding but also storage lower urinary tract symptoms after brachytherapy.

Diagnosis of complex renal cystic masses and solid renal lesions using PET imaging: comparison of 11C-acetate and 18F-FDG PET imaging.

PURPOSE: The study aims to assess the usefulness of PET with C-acetate and F-FDG to differentiate renal cell carcinoma (RCC) from complicated renal cysts. METHODS: Thirty-one patients were enrolled, 14 patients with complicated renal cysts (12 with Bosniak III and 2 with Bosniak IV) and 17 patients with 19 solid renal tumors. The patients underwent both C-acetate PET and FDG PET. Nephrectomy or partial nephrectomy was performed after the PET scans. RESULTS: In 29 patients, 32 renal lesions were diagnosed as RCC. Twenty-three of the 32 RCCs (72%) had positive C-acetate PET findings, whereas only 7 FDG PET studies were positive (22%). Considering the relationship between tumor size measured by macroscopic appearance of resected tumors and PET results, 22 of 25 (88%) tumors more than 1.5 cm showed positive C-acetate PET findings. In 12 patients with Bosniak III renal cysts, 10 renal lesions were diagnosed as RCC. In this subgroup, 5 of the 10 RCCs (50%) had positive C-acetate PET findings, whereas 2 RCCs (20%) had positive FDG PET findings. None of the cases with benign findings had positive C-acetate PET or FDG PET scans. CONCLUSIONS: C-acetate PET demonstrates a pronounced increase in tracer uptake in RCC, especially in renal tumors more than 1.5 cm, and displays a higher sensitivity than FDG PET. These preliminary data show that C-acetate may be a useful PET tracer to exclude RCC in complex renal cysts.

[A case on hemodialysis with castration-resistant prostate cancer which responded to combination chemotherapy with docetaxel and prednisolone].

A 71-year-old man on hemodialysis was admitted for castration-resistant prostate cancer. He received chemotherapy with docetaxel(60mg/m2 every 3 weeks)and prednisolone(10mg/day). As severe adverse reactions due to chemotherapy were not encountered, he could receive chemotherapy in our outpatient clinic. A total of four courses of chemotherapy resulted in a 56% reduction in PSA, which was judged as PR. Chemotherapy with docetaxel and prednisolone can be safely carried out for a patient with castration-resistant prostate cancer, even while on hemodialysis with the usual dose of docetaxel.

Fatty acid synthase is a key target in multiple essential tumor functions of prostate cancer: uptake of radiolabeled acetate as a predictor of the targeted therapy outcome.

Fatty acid synthase (FASN) expression is elevated in several cancers, and this over-expression is associated with poor prognosis. Inhibitors of FASN, such as orlistat, reportedly show antitumor effects against cancers that over-express FASN, making FASN a promising therapeutic target. However, large variations in FASN expression levels in individual tumors have been observed, and methods to predict FASN-targeted therapy outcome before treatment are required to avoid unnecessary treatment. In addition, how FASN inhibition affects tumor progression remains unclear. Here, we showed the method to predict FASN-targeted therapy outcome using radiolabeled acetate uptake and presented mechanisms of FASN inhibition with human prostate cancer cell lines, to provide the treatment strategy of FASN-targeted therapy. We revealed that tumor uptake of radiolabeled acetate reflected the FASN expression levels and sensitivity to FASN-targeted therapy with orlistat in vitro and in vivo. FASN-targeted therapy was noticeably effective against tumors with high FASN expression, which was indicated by high acetate uptake. To examine mechanisms, we established FASN knockdown prostate cancer cells by transduction of short-hairpin RNA against FASN and investigated the characteristics by analyses on morphology and cell behavior and microarray-based gene expression profiling. FASN inhibition not only suppressed cell proliferation but prevented pseudopodia formation and suppressed cell adhesion, migration, and invasion. FASN inhibition also suppressed genes involved in production of intracellular second messenger arachidonic acid and androgen hormones, both of which promote tumor progression. Collectively, our data demonstrated that uptake of radiolabeled acetate is a useful predictor of FASN-targeted therapy outcome. This suggests that [1-(11)C]acetate positron emission tomography (PET) could be a powerful tool to accomplish personalized FASN-targeted therapy by non-invasive visualization of tumor acetate uptake and selection of responsive tumors. FASN-targeted therapy could be an effective treatment to suppress multiple steps related to tumor progression in prostate cancers selected by [1-(11)C]acetate PET.

Drugs interacting with organic anion transporter-1 affect uptake of Tc-99m-mercaptoacetyl-triglycine (MAG3) in the human kidney: therapeutic drug interaction in Tc-99m-MAG3 diagnosis of renal function and possible application of Tc-99m-MAG3 for drug development.

INTRODUCTION: Renal uptake of Tc-99m-MG3 involves organic anion transporter (OAT). Treatment with drugs showing OAT affinity might interfere with renal uptake of Tc-99m-MAG3, leading to misinterpretation in Tc-99m-MAG3. This study was conducted to discuss a possible drug interference with Tc-99m-MAG3 diagnosis on OAT sites. METHODS: Renal uptake and plasma clearance of Tc-99m-MAG3 were analyzed in healthy volunteers under control and OAT1 and OAT3 related drug treatment conditions. An in vitro uptake study using OAT1 or OAT3 expressing cells was also conducted. RESULTS: Both PAH and probenecid treatment induced delays in Tc-99m-MAG3 clearance from blood, and reductions in the renal uptake clearance. As a result, the normalized effective renal plasma flow estimated from Tc-99m-MAG3 clearance was significantly underestimated, whereas the glomerular filtration rate estimated from plasma creatinine levels was unchanged. The transport activity of Tc-99m-MAG3 was higher in OAT1-expressing cells than in OAT3-expressing cells. CONCLUSION: Drugs with OAT1 affinity affect the renal uptake of Tc-99m-MAG3 and blood clearance. This might cause misinterpretation of functional diagnosis of the kidney using Tc-99m-MAG3.

Monoclonal antibody RM2 as a potential ligand for a new immunotracer for prostate cancer imaging.

OBJECTIVES: To investigate the potential of monoclonal antibody (mAb) RM2 as a ligand for a radioimmunotracer for prostate cancer imaging. METHODS: Labeling was conducted with mAb RM2 and (125)I using the chloramine-T method. The cell study was conducted with PC-3 and LNCaP, which are prostate cancer cell lines, and MCF-7, which is a breast cancer cell line. The cells were treated or untreated with unlabeled mAb RM2 to block the haptoglobin-ß chains expressed on the surface of the prostate cancer cells. (125)I-mAb RM2 was added into the cell culture media and cellular uptake of (125)I-mAb RM2 was evaluated at 1, 3 and 6 hours of incubation. For the in vivo biodistribution study, PC-3 cells were implanted in athymic male mice. The animals were injected intravenously with (125)I-mAb RM2. At 24, 48 and 72 hours after tracer injection, the animals were sacrificed and the activity levels of blood and tissue samples were determined. RESULTS: The uptake of (125)I-mAb RM2 in the PC-3 and LNCaP cells increased according to the incubation time, while the uptake of (125)I-mAb RM2 in MCF-7 cells did not show any increase up to 6 hours. The increase of (125)I-RM2 uptake was not observed when the PC-3 and LNCaP cells were pre-treated with unlabeled RM2. In the biodistribution studies, (125)I-mAb RM2 showed marked uptake into the implanted PC-3 cells. In PC-3 tumor-bearing mice, the tumor muscle ratio of (125)I-RM2 was increased for up to 72 hours in a time-dependent manner. CONCLUSIONS: (125)I-mAb RM2 showed excellent prostate cancer cell targeting in vitro and in vivo. Therefore, mAb RM2 seems to be a potential candidate for an immunoligand for prostate cancer imaging.

Radiolabeled Cu-ATSM as a novel indicator of overreduced intracellular state due to mitochondrial dysfunction: studies with mitochondrial DNA-less ρ0 cells and cybrids carrying MELAS mitochondrial DNA mutation.

OBJECTIVES: Radiolabeled Cu-diacetyl-bis (N(4)-methylthiosemicarbazone) (*Cu-ATSM), including (60/62/64)Cu-ATSM, is a potential imaging agent of hypoxic tumors for positron emission tomography (PET). We have reported that *Cu-ATSM is trapped in tumor cells under intracellular overreduced states, e.g., hypoxia. Here we evaluated *Cu-ATSM as an indicator of intracellular overreduced states in mitochondrial disorders using cell lines with mitochondrial dysfunction. METHODS: Mitochondrial DNA-less ρ(0)206 cells; the parental 143B human osteosarcoma cells; the cybrids carrying mutated mitochondria from a patient of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) (2SD); and that carrying wild-type one (2SA) were used. Cells were treated under normoxia or hypoxia, and (64)Cu-ATSM uptake was examined to compare it with levels of biological reductant NADH and NADPH. RESULTS: ρ(0)206 cells showed higher (64)Cu-ATSM uptake than control 143B cells under normoxia, whereas (64)Cu-ATSM uptake was not significantly increased under hypoxia in ρ(0)206 cells. Additionally, (64)Cu-ATSM uptake showed correlate change to the NADH and NADPH levels, but not oxygenic conditions. 2SD cells showed increased (64)Cu-ATSM uptake under normoxia as compared with the control 2SA, and (64)Cu-ATSM uptake followed NADH and NADPH levels, but not oxygenic conditions. CONCLUSIONS: (64)Cu-ATSM accumulated in cells with overreduced states due to mitochondrial dysfunction, even under normoxia. We recently reported that (62)Cu-ATSM-PET can visualize stroke-like episodes maintaining oxygen supply in MELAS patients. Taken together, our data indicate that *Cu-ATSM uptake reflects overreduced intracellular states, despite oxygenic conditions; thus, *Cu-ATSM would be a promising marker of intracellular overreduced states for disorders with mitochondrial dysfunction, such as MELAS, Parkinson's disease and Alzheimer's disease.

Antimuscarinics suppress adenosine triphosphate and prostaglandin E2 release from urothelium with potential improvement in detrusor overactivity in rats with cerebral infarction.

PURPOSE: Antimuscarinics improve detrusor overactivity. We evaluated the effects and action mechanisms of imidafenacin (Kyorin Pharmaceutical, Tokyo, Japan), a novel therapeutic agent for overactive bladder with antimuscarinic activity, on mediator release from urothelium and detrusor overactivity induced by cerebral infarction. MATERIALS AND METHODS: Bladder hydrodistention was achieved by intravesical infusion of Krebs solution. Bladder adenosine triphosphate and prostaglandin E(2) were measured in the presence and absence of anticholinergics using luciferin-luciferase assay and enzyme-linked immunoassay, respectively. Cerebral infarction was induced in rats by occluding the left middle cerebral artery. The effects of intravenous imidafenacin on bladder function were examined using cystometry in rats with cerebral infarction and in those pretreated with resiniferatoxin. RESULTS: Increased intravesical adenosine triphosphate and prostaglandin E(2) were shown by induced distention of isolated rat bladders. Imidafenacin and darifenacin (Kemprotec, Middlesbrough, United Kingdom) significantly suppressed the increases in adenosine triphosphate and prostaglandin E(2). Decreased bladder capacity was observed in rats with cerebral infarction. Detrusor overactivity was suppressed with a minimum intravenous dose of 0.001 mg/kg imidafenacin. The effects of imidafenacin were not noted in rats pretreated with resiniferatoxin. CONCLUSIONS: Results support the hypothesis or suggest that imidafenacin improves cerebral infarction induced detrusor overactivity by suppressing peripheral C-fibers. This effect is thought to be associated with suppression of the release of adenosine triphosphate and prostaglandin E(2) from the urothelium.

[Combination chemotherapy of paclitaxel, carboplatin and gemcitabine in patients who have received prior cisplatin-based chemotherapy].

The objective of this study was to evaluate the efficacy and toxicity of combination chemotherapy with paclitaxel, carboplatin and gemcitabine in patients with advanced urothelial carcinoma, who have received prior cisplatin-based chemotherapy. Eligible patients had pathologically proven measurable metastatic urothelial carcinoma. Between April 2005 and May 2009, 8 patients with a mean age of 7 0 years were treated every 3 weeks with paclitaxel (200 mg/m² on day 1), carboplatin (AUC= 5/body on day 1) and gemcitabine (800 mg/m² on day 1 and 8). A total of 4 0 (median 4) cycles were administered. None of the 8 patients achieved a complete response(CR), but 3 patients (37. 5%) achieved a partial response (PR) and 3 were stable with the disease(SD). The median overall survival time and the median progression-free survival time were 8. 0 and 4. 5 months, respectively. Grade 4 hematological toxicities included neutropenia in 6 cycles (15. 0%), thrombocytopenia in 8 cycles (20. 0%) and anemia in 11 cycles (27. 5%). Three of the 8 patients had febrile neutropenic episodes, and no toxic death was observed. Our results suggest that the combination chemotherapy of paclitaxel, carboplatin and gemcitabine was effective, and an acceptable treatment for patients with advanced urothelial carcinoma who have received prior cisplatin-based chemotherapy.

Effect of corticotropin-releasing factor receptor antagonist on psychologically suppressed masculine sexual behavior in rats.

INTRODUCTION: Corticotropin-releasing factor (CRF) coordinates various responses of the body to stress, and CRF receptors are important targets of treatment for stress-related disorders. AIM: To investigate the effect of a nonselective CRF receptor antagonist, astressin, on suppression of masculine sexual behavior by psychological stress in rats. METHODS: First, we investigated the influence of psychological stress, induced 2 hours per day for three consecutive days, on sexual behavior. Then, rats were divided into 4 groups: a control group, an astressin administration group (A), a psychological stress loading group (PS), and a psychological stress loading and astressin administration group (PS + A). The rats were exposed to sham or psychological stress for three consecutive days. After the last stress loading, the rats were injected with vehicle or astressin, and their sexual behavior was observed. We also measured serum levels of adrenocorticotropic hormone (ACTH). MAIN OUTCOME MEASURE: The effects of astressin on sexual behavior and serum levels of ACTH in rats affected by psychological stress were determined. RESULTS: Sexual behavior was reduced after psychological stress loading. The PS rats had significantly longer mount, intromission, and ejaculation latencies and lower ejaculation frequency than did the control, A, and PS + A rats. The intromission latency and ejaculation frequency in the PS + A rats did not achieve the level observed in the controls. There was no significant difference in these parameters between the control and A rats. Serum ACTH levels were significantly lower in PS + A rats than in PS rats. CONCLUSIONS: Psychologically suppressed masculine sexual behavior could be partially recovered with astressin administration in rats. These data provide a rationale for the further study of CRF receptor antagonists as novel agents for treating psychological sexual disorders.

Early response assessment in prostate carcinoma by ¹8F-fluorothymidine following anticancer therapy with docetaxel using preclinical tumour models.

PURPOSE: The aim of the study was to assess the potential usefulness of 3-deoxy-3-(18)F-fluorothymidine (FLT) as a radiopharmaceutical for imaging the early therapeutic effects of docetaxel (DTX) on tumour proliferation in hormone-refractory prostate cancer (HRPC). METHODS: Cells of the androgen-independent human prostate tumour cell line, 22Rv1, were implanted in athymic male mice. Approximately 3 weeks after cell implantation, the mice were treated with DTX or vehicle. Before and after the treatment, the mice were imaged with a microPET-Focus-F120 scanner (Concorde Microsystems, Knoxville, TN, USA) using FLT and (18)F-fluorodeoxyglucose (FDG). Tracer accumulations in the tumours were then analysed and compared with the proliferation activity and apoptotic index of the tumours. In a separate cell study, 22Rv1 cells were treated with DTX, then incubated with FLT or FDG and examined for their tracer uptake. RESULTS: The microPET imaging showed a significant decrease of FLT uptake in tumours after administration of DTX, while the changes of FDG uptake were minimal. Immunohistochemical analysis of the tumours revealed that the changes of FLT uptake were well correlated with those of proliferation activity but not with the apoptotic index. In vitro studies demonstrated that the significant decrease of FLT uptake in the cells after incubation with DTX correlated with the % S-phase cell fraction, while there were only minimal changes in the prostate-specific antigen concentration of the cell medium and FDG uptake in the cells. CONCLUSION: These results indicate that FLT is a promising tracer for monitoring the early effects of anticancer therapy with DTX in patients with HRPC.

Urethral Sensations are Related to the Development of Detrusor Overactivity.

Urgency is the core symptom of the overactive bladder symptom complex, but the underlying mechanisms are not fully understood. Clinical findings have led to the assumption that bladder outlet obstruction (BOO) caused by benign prostatic enlargement (BPE) induces storage symptoms and detrusor overactivity. Presumably, BOO by BPE accounts for urgency; however, urgency is not always caused by BOO. Sensory nerves in the wall of the urethra fire in response to urethral fluid flow, and this activity initiates bladder contractions in the quiescent bladder and augments ongoing contractions in the active bladder. In humans, prostatic urethral anesthesia results in significant increases in bladder capacity among BPH patients without neurological diseases, therefore sensory stimuli from an anatomically altered prostatic urethra has the possibility to induce urgency and detrusor overactivity. Studies in animals demonstrate the basis for an excitatory urethra to bladder reflex. Urethral stimulation by prostaglandin E2 induces an excitatory effect on micturition reflex by activation of C-fiber afferent nerves. α1A -adrenoceptor blocker has an inhibitory effect on the micturition reflex, suggesting excitatory urethra to bladder reflex is mediated by α1A -adrenoceptor. Even if there is no obstruction, increase in urethral sensory due to BPE may induce the development of the detrusor overactivity.

Assessment of Therapeutic Effect of Sunitinib by (11)C-Acetate PET Compared with FDG PET Imaging in a Patient with Metastatic Renal Cell Carcinoma.

Although sunitinib shows a high response rate in patients with untreated metastatic renal cell carcinoma (mRCC), quite a few patients show no therapeutic effect. Therefore, it is crucial to distinguish the patients who respond to sunitinib from those who do not as early as possible after the administration of the therapy. We herein report a case of mRCC in which (11)C-acetate (AC) positron emission tomography (PET) showed an early therapeutic effect of sunitinib treatment 4 weeks after its administration.

[Nodular fasciitis arose in the pelvis : a case report].

A 58-year-old woman presented to our emergency room with cystitis-like symptoms and macroscopic hematuria. Her symptoms were improved by the administration of an antibiotic, but transabdominal ultrasonography revealed a mass in her pelvis. The pelvic magnetic resonance imaging (MRI) depicted a solid tumor in the retropubic space. The patient requested hasty surgical excision of the tumor, rather than the conservative treatment after the diagnosis by cytology and biopsy. The postoperative histopathological examination revealed nodular fasciitis. She has been followed up for 8 months without any evidence of local recurrence. Nodular fasciitis is a mesenchymal lesion of proliferated fibroblast and commonly occurs in the subcutaneous tissue of the extremities. Frequently, it resembles a sarcoma, but it is said to be a benign disorder. In the urological domain, 14 intravesical cases have been reported. To our knowledge, this is the first case of the nodular fasciitis arising in the pelvis. We report this case and discuss the literature.

Selective α1A-blocker improves bladder storage function in rats via suppression of C-fiber afferent activity.

PURPOSE: In the present study, we used animal models to investigate whether the selective α(1A)-blocker silodosin exerts inhibitory effects on detrusor overactivity by modulating C-fiber afferent activity. METHODS: To desensitize C-fiber afferents, 0.3 mg/kg of resiniferatoxin (RTX) was subcutaneously injected into some female Sprague-Dawley rats 2 days before creation of each model. (1) Left middle cerebral artery occlusion was performed to create a cerebral infarction (CI) model (CI rats). The effects of intravenous (i.v.) and intrathecal (i.t.) administrations of silodosin on cystometrography parameters were evaluated in conscious rats. (2) Rhythmic bladder pressure was recorded in rats under urethane anesthesia. Prostaglandin (PG) E(2) (0.4 mg/mL) was continuously administered intraurethrally, and the effects of intra-arterial (i.a.) silodosin on the micturition reflex (MR) were investigated. RESULTS: (1) Silodosin (i.v.) dose-dependently increased bladder capacity (BC) in CI rats without decreasing bladder contraction pressure, but had no effects on BC in RTX-CI rats. Silodosin (i.t.) markedly increased BC in CI rats, but not in RTX-CI rats. (2) After intraurethral administration of PGE(2), the bladder contraction interval (BCI) was markedly reduced in non-RTX rats, but unchanged in RTX rats. Silodosin (i.a.) significantly prolonged BCI in non-RTX rats receiving intraurethral PGE(2). CONCLUSIONS: These results suggest that the α(1A)-AR subtype activates C-fiber afferents, and that consequently α(1A)-blockade can improve bladder storage function.