Effects of short‐term partial bladder outlet obstruction on the rabbit detrusor: An ultrastructural study

Abstract

It has been shown previously that partial bladder outlet obstruction in the rabbit results in changes in detrusor contractility and biochemical profile [Malkowicz et al., 1986]. The present study was conducted in the same animal model to define the nature and evolution of concomitant structural neuromuscular changes in the detrusor, as the basis for its altered function following partial outlet obstruction. Twenty‐five New Zealand White rabbits, including three normal controls, were used. The bladder was excised in 15 rabbits at various intervals 1–14 days postoperatively. In the remaining seven rabbits, the obstruction was relieved after 7 days, and the bladders were excised 14 or 28 days later. Multiple samples of the midbody detrusor were obtained from each specimen and processed for electron microscopy by standard techniques. Changes were observed in the smooth muscle, interstitial, and neural compartments. The muscular changes included a combination of muscle cell degeneration and regeneration, and widening of intercellular spaces with deposition of basal lamina‐like material. Both degenerative and regenerative muscle cell profiles were uncommon in the control and 1 day obstructed samples, frequent in the 3–7 day obstructed samples, and less frequent in the 14 day obstructed samples. The spaces between individual muscle cells appeared to become increasingly wider in the 3–14 day obstructed samples. The ultrastructure of smooth muscle in samples from both deobstructed groups was similar to controls, except for thickened basal laminae of muscle cells and consistently widened intercellular spaces. The interstitial compartment appeared to become progressively exaggerated with increasing deposits of collagen and elastin in the 3–14 day obstructed samples; these changes persisted in samples from both deobstructed groups. In regard to the neural compartment, degeneration of both cholinergic and adrenergic nerves with loss of neuroeffector junctions was observed in the 3–7 day obstructed samples; axonal regeneration was seen with re‐establishment of the junctions in the 14 day obstructed and both deobstructed groups. It is concluded that partial bladder outlet obstruction in the rabbit results in partially reversible neuromuscular changes in the detrusor, which can explain the resultant alterations in detrusor contractility and biochemical profile.

Regeneration of detrusor muscle after subtotal cystectomy in the rat: Effects on contractile proteins and bladder mechanics

“…Mature smooth muscle cells will undergo hypertrophy within the muscle bundles in a fashion similar [Elbadawi et al, 1989;Gosling et al, 2000] to that in the rat bladder. Adding to this, a large number of subserosal ®broblasts become transformed [Buoro et al, 1993;Chiavegato et al, 1993;Levin et al, 1995] to myo®broblasts (containing vimentin, smooth muscle actin, and non-muscle myosin) and ®nally to fetal-type smooth muscle cells (containing vimentin, desmin, smooth muscle actin, and smooth muscle myosin).…”

Distinctive Ultrastructural Pathology of Nonulcerative Interstitial Cystitis

“…It has not been observed in samples of either normal or dysfunctional human detrusor processed for electron microscopic study by identical procedures [52][53][54][55]. Furthermore, it lacked the known ultrastructural features of degenerating, regen erating, and hypertrophic smooth muscle cells [55,57,58], and was associated in all the cases with changes in other tissue elements that clearly were due to edema.…”

Hypertrophy of visceral smooth muscle

“…Urinary bladder hypertrophy can be obtained by placing a ligature around the urethra to reduce the lumen (Brent and Stephens 1975;Mattiasson and Uvelius 1982;Levin et al 1984;Steers and De Groat 1988;Elbadawi et al 1989). These experiments are unlike human prostatism in that the partial obstruction is established abruptly 1 There is little or no change in intestinal muscle cell sizes in parenteral nutrition (Nygaard 1967;Nemeth et al 1983).…”

“…Degeneration may be more common in human material with impairments of longer duration, often accompanied by inflammation. In the short-term obstructed bladder of rabbits, Elbadawi et al (1989) observed that over 50% of the cell profiles were disintegrating muscle cells.…”