Quantitative analysis of intercellular changes in the short‐term partially obstructed rabbit detrusor

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Abstract
In a previous qualitative ultrastructural study, we developed the impression that muscle cell changes following partial outlet obstruction of the rabbit bladder are associated with an increase in the width of intercellular spaces [Elbadawi et al., 1989]. In the present study, we tested that impression by direct measurement of intercellular distances using a simple method that we devised for that purpose. The material for study was obtained from 25 New Zealand White male rabbits, including three normal controls, 15 with partial bladder outlet obstruction, and seven with 7‐day obstruction followed by deobstruction. Specimens from the body detrusor were obtained from each animal and processed for electron microscopy by standard methods. Multiple sections from each sample were studied. A total of 3,889 individual measurements made in 163 electron photomicrographic prints were evaluated statistically. A statistically significant progressive increase in the width of intercellular spaces was observed over the 14‐day period of obstruction, confirming our previous qualitative impression. On the other hand, there were no significant differences in the width of spaces between the deobstructed and the 7‐day obstructed detrusor. Our observations underscore the fact that evaluation of the intercellular compartment by measuring its volume density does not reflect the true width of spaces between muscle cells of the pathologically altered detrusor. The herein verified progressively wider separation of detrusor muscle cells following partial bladder outlet obstruction probably hampers both electrotonic and mechanical coupling of muscle cells, thus preventing efficient and coordinated detrusor muscular responses to neural stimuli.