DENERVATION AND OUTLET OBSTRUCTION INDUCE A NET SYNTHESIS OF CONTRACTILE AND CYTOSKELETAL PROTEINS IN THE URINARY-BLADDER OF THE MALE RAT

The concentrations of the contractile proteins actin and myosin and th e cytoskeletal protein desmin were determined in urinary bladders from normal rats, and from rats with bladder outlet obstruction or denerva tion. Ten days of obstruction or total denervation by bilateral remova l of the pelvic ganglia resulted in an almost fourfold increase in bla dder weight. Actin and myosin concentrations did not change significan tly. The total amount of actin was 1624 +/- 235 mu g in the control bl adder. In the obstructed and denervated bladders it increased signific antly to 6277 +/- 648 mu g and 7671 +/- 835 mu g, respectively. The de smin/actin ratio was 0.237 +/- 0.012 in the control bladders, and incr eased significantly to 0.369 +/- 0.015 in the obstructed and 0.343 +/- 0.022 in the denervated bladders. Partial denervation by removal of t he pelvic ganglion on one side only increased bladder weight by 52%, b ut did not increase the desmin/actin ratio. The content of actin in su ch bladders increased by 82%. Both obstruction (which increases the fu nctional load of the detrusor muscle cells) and denervation (which pro duces bladder paralysis) are known to induce hypertrophy of the detrus or smooth muscle cells. The study shows that the desmin/actin ratio an d the total amount of contractile proteins increase in response to the hypertrophy as such, and not to the work performed by the smooth musc le cells, and that the nerves have no trophic influence on the growth response. Also, even a limited lesion of the bladder innervation is as sociated with growth and a net increase in the amount of contractile p roteins.