Epidemiological, genetic and neuropharmacological evidence links disorders of voiding and anxiety. CRF may participate in these events and warrants further investigation as a therapeutic target in the treatment of OAB and interstitial cystitis.
These results provide a rationale for the early use of phosphodiesterase-5 inhibition following radical prostatectomy or extensive pelvic surgery, during which there may be injury to the cavernous nerves, to aid in the return of erectile function.
AIMS
The purpose of this investigation was to develop a non-invasive, objective, and unprompted method to characterize real-time bladder sensation.
METHODS
Volunteers with and without overactive bladder (OAB) were prospectively enrolled in a preliminary accelerated hydration study. Participants drank 2L Gatorade-G2® and recorded real-time sensation (0–100% scale) and standardized verbal sensory thresholds using a novel, touch-screen “sensation meter.” 3D bladder ultrasound images were recorded throughout fillings for a subset of participants. Sensation data were recorded for two consecutive complete fill-void cycles.
RESULTS
Data from 14 normal and 12 OAB participants were obtained (ICIq-OAB-5a = 0 vs. ≥3). Filling duration decreased in fill2 compared to fill1, but volume did not significantly change. In normals, adjacent verbal sensory thresholds (within fill) showed no overlap, and identical thresholds (between fill) were similar, demonstrating effective differentiation between degrees of %bladder capacity. In OAB, within-fill overlaps and between-fill differences were identified. Real-time %capacity-sensation curves left shifted from fill1 to fill2 in normals, consistent with expected viscoelastic behavior, but unexpectedly right shifted in OAB. 3D ultrasound volume data showed that fill rates started slowly and ramped up with variable end points.
CONCLUSIONS
This study establishes a non-invasive means to evaluate real-time bladder sensation using a two-fill accelerated hydration protocol and a sensation meter. Verbal thresholds were inconsistent in OAB, and the right shift in OAB %capacity–sensation curve suggests potential biomechanical and/or sensitization changes. This methodology could be used to gain valuable information on different forms of OAB in a completely non-invasive way.
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.
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