Effects of Denervation and Infravesical Obstruction in the Rat Urinary Bladder

Sammanfattning: Median micturition volume decreased early after partial outlet obstruction, 24 hrs total obstruction and hemidenervation. Degeneration release of transmitter may explain this, assuming that bladder wall distension causes nerve degeneration. Micturition pressure decreased simultaneously in the partially denervated and 24 hrs obstructed groups, probably due to the reduced number of functionally intact nerve terminals. Atropine resistance, not present in man, except in pathological conditions, increased early in all groups, but returned to normal with time, except in the 24 hrs obstructed group where it finally reached subnormal levels. Persistingly increased micturition volumes were found from 7 and 10 days after hemidenervation and 24 hrs total obstruction. This may be attributed to a non-recovery of afferent, sensory nerves after initial damage. However, micturition pressure normalized with time for both groups, suggesting a recovery of motor function. A 50% increase was found in ganglion cell volume 7 weeks after contralateral ganglionectomy and an 80% increase 6 - 8 weeks after inducing partial obstruction. The latter process was found to be reversible after removing the obstruction. It seems that there exists a maximal size of the ganglion cells. Heavy staining of LDH was found in pelvic ganglion neurons of both control and obstructed animals. A high capacity for glycolysis in anoxia could be expected in the nerves of the bladder under normal conditions as well as under obstruction. AVP concentration was decreased, but total AVP content increased in the partially obstructed bladder. Also, maximal response to AVP in vitro was significantly decreased and cystometry showed decreased excitability by AVP. These phenomena are parallel to those of substance P. Both partial obstruction and total denervation caused an increase in total amounts of actin and myosin and a higher desmin/actin ratio after 10 days. Even a limited bladder lesion, unilateral ganglionectomy, induced g a net syntesis of contractile proteins. The extent of growth, rather than the functional status, seems to determine the degree of net synthesis of contractile and cytoskeletal proteins.