Three dimensional registration of mechanical bladder activity using polystyrene fluorescent spheres: A technical note

Regional differences in bladder enlargement and in vitro contractility after outlet obstruction in the rabbit

PURPOSE

Bladder outlet obstruction leads to bladder enlargement and subsequent decreases in contractile function in vivo and in vitro. We determined whether there were regional differences in bladder wall properties and in vitro contractile responses after 2 weeks of bladder outlet obstruction.

MATERIALS AND METHODS

Male rabbits underwent cystometry. The bladder was then filled to 40 ml. and the surface was marked with 2-zero silk knots placed approximately 1 cm. apart. The distance between the knots was measured at 20, 40 and 80 ml. The animals then underwent the creation of surgical obstruction. After 2 weeks the obstruction was removed. Cystometry and measurements were repeated and strips were obtained from defined dorsal and ventral areas. Contractile responses to electrical field stimulation, adenosine triphosphate, carbachol and KCl were determined and compared with strips from unobstructed controls.

RESULTS

In vivo expansion during bladder filling occurred evenly throughout the bladder wall in controls and the contractile response to all stimuli was similar in ventral and dorsal strips. After 2 weeks of bladder outlet obstruction the upper dome expanded to a significantly higher degree than the lower bladder body. The response to all stimuli was significantly reduced after bladder outlet obstruction and there was a significantly decreased response to all stimuli in dorsal compared with ventral strips. Strips from the dorsal midline showed a relaxation response to electrical field stimulation at low frequencies, whereas all ventral strips contracted.

CONCLUSIONS

Functional remodeling after bladder outlet obstruction is a process that does not occur to the same extent throughout the bladder. The obstructed bladder is an inhomogeneous organ with significant regional differences in mechanical and pharmacological properties.

Structural and functional responses of the bullfrog urinary bladder to distension caused by hydrostatic pressure gradients

The responses to mucosal pressure elevation (physiological pressure: PP) were compared to responses to serosal pressure elevation (non-physiological pressure: NPP) in bullfrog urinary bladders (Rana catesbeiana). The bladders were mounted on vertical chambers as flat sheets. Distension was applied with 98.07 Pa. pressure gradients. PP resulted in increases in transepithelial electrical potential difference (TEP) and short-circuit current (SCC). Electrical resistance (R), urea permeability (P(urea)) and net water flux (J( v)) were not effected. NPP resulted in decreases in TEP (38%), SCC (13%), and R (36%). While P(urea) (97%) and J(v) (96%) increased. PP caused little or no change in the electron microscopic structure of frog bladder while NPP caused irreversible dilation of the lateral intercellular spaces. There were no observable changes in tight junctions under PP or NPP. The subepithelial elements of the bladder became detached from the epithelial layer during NPP suggesting a role for them during PP.

'Rules of conduct': some practical guidelines for testing motor-nerve conduction

The testing of nerve conduction using electromyography (EMG) is a frequently used diagnostic method for the identification of various neuropathies. The present article illustrates a variety of conditions on the basis of clinical data, and suggests how one can obtain the best results by observing a few simple rules.