Adam P. Klausner

The role of corticotropin releasing factor and its antagonist, astressin, on micturition in the rat

The purpose of this investigation was to evaluate the role of corticotropin releasing factor (CRF) on micturition. CRF is involved in the endocrine and central nervous system responses to stress and is also expressed in sites responsible for the control of micturition. In this investigation, cystometric experiments were performed in awake and unrestrained Wistar rats and on Spontaneous Hypertensive Rats, which are used as a rodent model of detrusor overactivity and anxiety. In vitro effects of CRF were evaluated using strips of detrusor muscle in an organ bath preparation. CRF (6.0 microg) administered via intrathecal and intraperitoneal routes, but not intracerebroventricularly, lowered the micturition threshold. CRF reduced the intercontraction interval by 28% and 26% after intrathecal or intraperitoneal administration, respectively, and reduced micturition volume by 34.7% and 30.2%, respectively. In Wistar-Kyoto rats, 6.0 microg intrathecal CRF significantly reduced intercontraction interval (423 +/- 79 vs. 669 +/- 59 s) and micturition volume (0.30 +/- 0.04 vs. 0.69 +/- 0.07 ml) compared to controls that received saline vehicle. These effects were blocked by pretreatment with 6.0 mug intrathecal astressin, a potent CRF antagonist, demonstrating that the effects are CRF receptor mediated. In Spontaneous Hypertensive Rats, 6.0 mug intrathecal CRF was found to have minimal stimulatory effects on the bladder, whereas astressin reduced baseline detrusor overactivity. CRF had no direct contractile effects on detrusor muscle strips. These results demonstrate that in the absence of detrusor overactivity, CRF stimulates micturition when administered via the intrathecal or intraperitoneal routes. Further studies are needed to explore the possibility whether CRF antagonists are effective for detrusor overactivity and the overactive bladder syndrome.

Potential for control of detrusor smooth muscle spontaneous rhythmic contraction by cyclooxygenase products released by interstitial cells of Cajal

Interstitial cells of Cajal (ICCs) have been identified as pacemaker cells in the upper urinary tract and urethra, but the role of ICCs in the bladder remains to be determined. We tested the hypotheses that ICCs express cyclooxygenase (COX), and that COX products (prostaglandins), are the cause of spontaneous rhythmic contraction (SRC) of isolated strips of rabbit bladder free of urothelium. SRC was abolished by 10 μM indomethacin and ibuprofen (non‐selective COX inhibitors). SRC was concentration‐dependently inhibited by selective COX‐1 (SC‐560 and FR‐122047) and COX‐2 inhibitors (NS‐398 and LM‐1685), and by SC‐51089, a selective antagonist for the PGE‐2 receptor (EP) and ICI‐192,605 and SQ‐29,548, selective antagonists for thromboxane receptors (TP). The partial agonist/antagonist of the PGF‐2α receptor (FP), AL‐8810, inhibited SRC by ∼50%. Maximum inhibition was ∼90% by SC‐51089, ∼80–85% by the COX inhibitors and ∼70% by TP receptor antagonists. In the presence of ibuprofen to abolish SRC, PGE‐2, sulprostone, misoprostol, PGF‐2α and U‐46619 (thromboxane mimetic) caused rhythmic contractions that mimicked SRC. Fluorescence immunohistochemistry coupled with confocal laser scanning microscopy revealed that c‐Kit and vimentin co‐localized to interstitial cells surrounding detrusor smooth muscle bundles, indicating the presence of extensive ICCs in rabbit bladder. Co‐localization of COX‐1 and vimentin, and COX‐2 and vimentin by ICCs supports the hypothesis that ICCs were the predominant cell type in rabbit bladder expressing both COX isoforms. These data together suggest that ICCs appear to be an important source of prostaglandins that likely play a role in regulation of SRC. Additional studies on prostaglandin‐dependent SRC may generate opportunities for the application of novel treatments for disorders leading to overactive bladder.

Adaptation of the length-active tension relationship in rabbit detrusor

Studies have shown that the length-tension (L-T) relationships in airway and vascular smooth muscles are dynamic and can adapt to length changes over a period of time. Our prior studies have shown that the passive L-T relationship in rabbit detrusor smooth muscle (DSM) is also dynamic and that DSM exhibits adjustable passive stiffness (APS) characterized by a passive L-T curve that can shift along the length axis as a function of strain history and activation history. The present study demonstrates that the active L-T curve for DSM is also dynamic and that the peak active tension produced at a particular muscle length is a function of both strain and activation history. More specifically, this study reveals that the active L-T relationship, or curve, does not have a unique peak tension value with a single ascending and descending limb, but instead reveals that multiple ascending and descending limbs can be exhibited in the same DSM strip. This study also demonstrates that for DSM strips not stretched far enough to reveal a descending limb, the peak active tension produced by a maximal KCl-induced contraction at a short, passively slack muscle length of 3 mm was reduced by 58.6 +/- 4.1% (n = 15) following stretches to and contractions at threefold the original muscle length, 9 mm. Moreover, five subsequent contractions at the short muscle length displayed increasingly greater tension; active tension produced by the sixth contraction was 91.5 +/- 9.1% of that produced by the prestretch contraction at that length. Together, these findings indicate for the first time that DSM exhibits length adaptation, similar to vascular and airway smooth muscles. In addition, our findings demonstrate that preconditioning, APS and adaptation of the active L-T curve can each impact the maximum total tension observed at a particular DSM length.

The Influence of Psychiatric Comorbidities and Sexual Trauma on Lower Urinary Tract Symptoms in Female Veterans

PURPOSE We characterized the association of psychiatric comorbidities and sexual trauma with lower urinary tract symptoms in women. MATERIALS AND METHODS Consecutive women (121) referred for evaluation of lower urinary tract symptoms to a specialized urology clinic were given validated questionnaires including the Urogenital Distress Inventory-6 and Incontinence Impact Questionnaire-7. These data were then analyzed according to psychiatric comorbidities, history of sexual trauma, age, race and obstetric history. Baseline incidence of psychiatric comorbidity and sexual trauma was also compared to a control population (1,298) from which all patients were referred. RESULTS Women referred for evaluation of lower urinary tract symptoms had higher rates of psychiatric comorbidities (64.5% vs 25.9%, p <0.001) and sexual trauma (49.6% vs 20.1%, p <0.001) compared to those in the primary care clinic. Total survey scores for the Incontinence Impact Questionnaire-7 were significantly higher for patients with psychiatric comorbidities and sexual trauma (11.05 +/- 0.84) compared to scores of patients with neither of these conditions (7.6 +/- 1.02, p = 0.010). Stepwise multivariate regression analyses demonstrated that higher Urogenital Distress Inventory-6 scores were associated only with age younger than 50 years and history of miscarriage, and that higher Incontinence Impact Questionnaire-7 scores were associated only with psychiatric comorbidities and history of miscarriage. CONCLUSIONS Psychiatric comorbidities and sexual trauma are prevalent in female veterans presenting for evaluation of lower urinary tract symptoms and psychiatric comorbidities are associated with greater quality of life impact.

Potentiation of carbachol-induced detrusor smooth muscle contractions by β-adrenoceptor activation

In strips of rabbit bladder free of urothelium, the beta-adrenoceptor agonist, isoproterenol, significantly reduced basal detrusor smooth muscle tone and inhibited contractions produced by low concentrations of the muscarinic receptor agonist, carbachol. During a carbachol concentration-response curve, instead of inhibiting, isoproterenol strengthened contractions produced by high carbachol concentrations. Thus, the carbachol concentration-response curve was shifted by isoproterenol from a shallow, graded relationship, to a steep, switch-like relationship. The tyrosine kinase inhibitor, genistein, inhibited carbachol-induced contractions only in the presence of isoproterenol. Contraction produced by a single high carbachol concentration (1 microM) displayed 1 fast and 1 slow peak. In the presence of isoproterenol, the slow peak was not strengthened, but was delayed, and U-0126 (mitogen-activated protein kinase kinase inhibitor) selectively inhibited this delay concomitantly with inhibition of extracellular signal-regulated kinase (ERK) phosphorylation. Isoproterenol reduced ERK phosphorylation only in the absence of carbachol. These data support the concept that, by inhibiting weak contractions, potentiating strong contractions, and producing a more switch-like concentration-response curve, beta-adrenoceptor stimulation enhanced the effectiveness of muscarinic receptor-induced detrusor smooth muscle contraction. Moreover, beta-adrenoceptor stimulation changed the cellular mechanism by which carbachol produced contraction. The potential significance of multi-receptor and multi-cell crosstalk is discussed.

Rhythmic contraction generates adjustable passive stiffness in rabbit detrusor

The length-tension (L-T) relationships in airway and vascular smooth muscles have been shown to adapt with length changes over time. Our prior studies have shown that the active and passive L-T relationships in rabbit detrusor smooth muscle (DSM) can adapt and that DSM exhibits adjustable passive stiffness (APS) characterized by a passive L-T curve that is a function of strain and activation history. The present study demonstrates that passive tension due to APS can represent a substantial fraction of total tension over a broad length range. Our previous studies have shown that maximal KCl-induced contractions at short muscle lengths generate APS that is revealed by increased pseudo-steady-state passive tension at longer lengths compared with previous measurements at those lengths. The objective of the present study was to determine the mechanisms involved in APS generation. Increasing the number of KCl-induced contractions or the duration of a contraction increased the amount of APS generated. Furthermore, a fraction of APS was restored in calcium-free solution and was sensitive to the general serine and threonine protein kinase inhibitor staurosporine. Most importantly, rhythmic contraction (RC) generated APS, and because RC occurs spontaneously in human bladder, a physiological role for RC was potentially identified.

A pilot study to measure dynamic elasticity of the bladder during urodynamics

Previous studies using isolated strips of human detrusor muscle identified adjustable preload tension, a novel mechanism that acutely regulates detrusor wall tension. The purpose of this investigation was to develop a method to identify a correlate measure of adjustable preload tension during urodynamics.

Ureteroscopy with laser lithotripsy for urolithiasis in the spinal cord injury population.

Study design:Retrospective study.Objectives:The purpose of this investigation was to review the outcomes and safety of retrograde ureteroscopic laser lithotripsy (URS) for the treatment of urolithiasis in the spinal cord injury (SCI) population.Setting:Virginia, USA.Methods:All patients with SCI who underwent URS with holmium:YAG laser lithotripsy for urolithiasis over a 15-year period were identified. Stone size, location and number at presentation were recorded. Information regarding patient characteristics, intra-operative complications, surgical efficacy, stone clearance, peri-operative complications, and follow-up stone events was collected and analyzed.Results:A total of 67 URS procedures were performed on 29 SCI patients during the study period with an average follow-up of 3.4 years. Patients had an average of 2.3 ipsilateral ureteroscopies. The majority (85.1%) used indwelling catheters for long-term bladder management, and complete stone clearance after the first procedure was 34.3%. Of the 44 cases with residual stones >4 mm, 20 (45.5%) were secondary to technical or procedural limitations. The intra-operative complication rate was comparable to non-SCI studies at 1.5%, but peri-operative complications were significantly higher at 29.9% with the majority due to urosepsis. Factors associated with peri-operative complications include chronic obstructive pulmonary disease, motor incomplete injuries and lack of a pre-operative ureteral stent.Conclusion:URS in the SCI population is an effective treatment for ureteral or renal stones but may be associated with greater risks and reduced efficacy.Sponsorship:None.

Adjustable passive stiffness in mouse bladder: regulated by Rho kinase and elevated following partial bladder outlet obstruction

Detrusor smooth muscle (DSM) contributes to bladder wall tension during filling, and bladder wall deformation affects the signaling system that leads to urgency. The length-passive tension (L-T(p)) relationship in rabbit DSM can adapt with length changes over time and exhibits adjustable passive stiffness (APS) characterized by a L-T(p) curve that is a function of both activation and strain history. Muscle activation with KCl, carbachol (CCh), or prostaglandin E(2) at short muscle lengths can increase APS that is revealed by elevated pseudo-steady-state T(p) at longer lengths compared with prior T(p) measurements at those lengths, and APS generation is inhibited by the Rho Kinase (ROCK) inhibitor H-1152. In the current study, mouse bladder strips exhibited both KCl- and CCh-induced APS. Whole mouse bladders demonstrated APS which was measured as an increase in pressure during passive filling in calcium-free solution following CCh precontraction compared with pressure during filling without precontraction. In addition, CCh-induced APS in whole mouse bladder was inhibited by H-1152, indicating that ROCK activity may regulate bladder compliance during filling. Furthermore, APS in whole mouse bladder was elevated 2 wk after partial bladder outlet obstruction, suggesting that APS may be relevant in diseases affecting bladder mechanics. The presence of APS in mouse bladder will permit future studies of APS regulatory pathways and potential alterations of APS in disease models using knockout transgenetic mice.

Elevated steady-state bladder preload activates myosin phosphorylation: detrusor smooth muscle is a preload tension sensor.

In rabbit bladder wall (detrusor) muscle, the degree of tone induced during physiological filling (filling tone) is the sum of adjustable preload tension and autonomous contractile tension. The present study was designed to determine whether the level of filling tone is dependent on detrusor muscle length. Maximum active tension induced by KCl was parabolic in relation to length [tension increased from 70% to 100% of a reference length (L(ref)) and decreased at longer muscle lengths]. Filling tone, however, increased in a linear fashion from 70% to 120% L(ref). In the presence of ibuprofen to abolish autonomous contraction and retain adjustable preload tension, tension was reduced in strength but remained linearly dependent on length from 70% to 120% L(ref). In the absence of autonomous contraction, stretching detrusor muscle from 80% to 120% L(ref) still caused an increase in tone during PGE(2)-induced rhythmic contraction, suggesting that muscle stretch caused increases in detrusor muscle contractile sensitivity rather than in prostaglandin release. In the absence of autonomous contraction, the degree of adjustable preload tension and myosin phosphorylation increased when detrusor was stretched from 80% to 120% L(ref), but also displayed length-hysteresis, indicating that detrusor muscle senses preload rather than muscle length. Together, these data support the hypothesis that detrusor muscle acts as a preload tension sensor. Because detrusor muscle is in-series with neuronal mechanosensors responsible for urinary urgency, a more thorough understanding of detrusor muscle filling tone may reveal unique targets for therapeutic intervention of contractile disorders such as overactive bladder.