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

Abstract

The aim of the present study was to determine to what extent adult rats can produce new contracting bladder muscle and to see if such newly formed bladder tissue possesses characteristic mechanical properties or whether the ability to recover mechanically is so pronounced that the prehistory of the bladder is unimportant. Subtotal cystectomy was performed in adult female rats, leading to a pronounced decrease in total bladder weight. At 10 weeks, bladder weight had normalized. The histological appearance of such bladders was similar to that of the controls. Active and passive length-tension relations for the detrusor muscle were determined in controls and up to 10 weeks after surgery. Immediately after surgery active and passive forces showed a leftward shift and maximum active force decreased markedly. With time the length-tension curves shifted back to normal, but a decreased active force still remained at 10 weeks. Detrusor actin concentration and detrusor myosin/actin ratio were unaffected by the subtotal cystectomy. Intermediate filament protein/actin ratio showed a significant but transitory increase. We conclude that there is a remarkable recovery of detrusor muscle function after subtotal cystectomy, leading to a normalization of optimum length for active force and a net synthesis of contractile and cytoskeletal proteins. The ability to produce active force does, however, not fully recover.

Nerve induced responses and force–velocity relations of regenerated detrusor muscle after subtotal cystectomy in the rat

“…The pharmacological properties were therefore close to those of normal bladder base. In a previous study [Frederiksen et al, 2001] we found, on the other hand, that the recovery of the rat bladder after subtotal cystectomy was mainly through regeneration of the bladder body. There is an interesting di¡erence between rat and rabbit bladder; contrary to the rabbit bladder the rat bladder is devoid of intramural ganglion cells [Gabella and Uvelius, 1990].…”

“…Saito et al [1996] found a decreased active pressure to ¢eld stimulation in vitro. In our previous study [Frederiksen et al, 2001], we found that the circumference of the bladder body for the development of maximal active force increased with time to normal. Maximal active force was in that study only about 60% of normal, suggesting that there is either a decreased amount of new detrusor muscle or that it has a decreased force producing ability.…”

“…The surgery and the subsequent growth of the supratrigonal segment of the detrusor [Frederiksen et al, 2001] had thus no impact on its pharmacological properties.…”

“…In a previous study [Frederiksen et al, 2001] we found, on the other hand, that the recovery of the rat bladder after subtotal cystectomy was mainly through regeneration of the bladder body rather than through an expansion of the bladder base. This eventually leads to an almost complete recovery of bladder morphology, weight and shape [Saito et al, 1996;Frederiksen et al, 2001], and a normalization of passive and active length-tension properties with a net synthesis of contractile proteins [Frederiksen et al, 2001]. It is, however, not known if the newly formed muscle has a normal maximum shortening velocity.…”

Nerve distribution in rat urinary bladder after incorporation of acellular matrix graft or subtotal cystectomy

“…Following subtotal cystectomy the remaining urinary bladder segment starts to grow [23,24]. Eventually the detrusor weighs as much as in control bladders.…”