Detrusor collagen content in the denervated rat urinary bladder.

Neurogenic bladder dysfunction was created in male rats by removal of the pelvic ganglia. The bladders were then emptied manually once daily, and kept free from infection. After 10 days or six weeks the bladders were taken out and the mucosa-submucosa was removed. The detrusors were then weighed and used for collagen assay. Detrusor weight increased 4.5 and six times after 10 days and six weeks, respectively. Total detrusor collagen increased 2.3 and 3.7 times, but due to the increase in detrusor weight the concentration decreased to 60 per cent of normal. The electron microscopic investigation showed that the cross-sectional area of the smooth muscle cells had increased fourfold after six weeks. The collagen fibrils were found mainly in the interstitial tissue between the muscle bundles. As these increased in size following the neurogenic lesion, the collagen-rich tissue component decreased relatively. Our conclusion is that frequent emptying and the avoidance of bladder infection protects the denervated rat urinary bladder wall from injuries that would otherwise lead to an increased collagen concentration.