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  • 1
    ISSN: 1434-0879
    Keywords: Actin ; Desmin ; Growth factors ; Myosin ; Urinary bladder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Systemic treatment with epidermal growth factor (EGF) induces growth of all wall layers in the urinary tract of pigs and rats. The present study was initiated to describe morphological and biochemical changes in the bladder smooth muscle from rats treated with EGF for 4 weeks. Eight-week-old female Wistar rats were treated with subcutaneous injections of vehicle (n=16) or EGF (n=8, 150 μg/kg per day) for 4 weeks. After EGF treatment the bladders were increased in weight [74.4±0.4 vs 122.1±0.5 mg, P〈0.001 (mean ± SEM)]. Sodium dedecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analyses of six bladders from each group revealed that the total amounts of actin, myosin and desmin were statistically significantly increased by 62%, 61% and 154%, respectively. The relative amounts of actin and myosin were unchanged whereas the desmin to actin ratio was significantly increased — as previously described in rat bladder smooth muscle hypertrophy. Light and electron microscopy of two bladders from each group revealed increased wall thickness involving all wall layers. The smooth muscle fibres at a midventral bladder location seemed only slightly hypertrophic — some degree of hyperplasia was therefore suspected. In conclusion, EGF treatment for 4 weeks induced a net synthesis of contractile and cytoskeletal proteins in the urinary bladder smooth muscle.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-0879
    Keywords: Urinary bladder ; Outlet obstruction ; Denervation ; Actin ; Myosin ; Desmin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The concentrations of the contractile proteins actin and myosin and the cytoskeletal protein desmin were determined in urinary bladders from normal rats, and from rats with bladder outlet obstruction or denervation. Ten days of obstruction or total denervation by bilateral removal of the pelvic ganglia resulted in an almost fourfold increase in bladder weight. Actin and myosin concentrations did not change significantly. The total amount of actin was 1624±235 μg in the control bladder. In the obstructed and denervated bladders it increased significantly to 6277±648 μg and 7671±835 μg, respectively. The desmin/actin ratio was 0.237±0.012 in the control bladders, and increased significantly to 0.369±0.015 in the obstructed and 0.343±0.022 in the denervated bladders. Partial denervation by removal of the pelvic ganglion on one side only increased bladder weight by 52%, but did not increase the desmin/actin ratio. The content of actin in such bladders increased by 82%. Both obstruction (which increases the functional load of the detrusor muscle cells) and denervation (which produces bladder paralysis) are known to induce hypertrophy of the detrusor smooth muscle cells. The study shows that the desmin/actin ratio and the total amount of contractile proteins increase in response to the hypertrophy as such, and not to the work performed by the smooth muscle cells, and that the nerves have no trophic influence on the growth response. Also, even a limited lesion of the bladder innervation is associated with growth and a net increase in the amount of contractile proteins.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-0879
    Keywords: Bladder smooth muscle ; Intermediate filaments ; Age ; Actin ; Myosin ; Force-velocity relation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The influence of old age on mechanical properties of the urinary bladder was investigated using smooth muscle strips from urinary bladders of control (14–16 weeks) and old-age (104 weeks) female Sprague-Dawley rats. Bladder weight of the aged rats had increased by about 30%. The maximal shortening velocity and stiffness in skinned activated urinary bladder fibers from old animals were unchanged compared to controls. The relative content of intermediate filament proteins to actin and the relative content of myosin to actin was unchanged. The concentration of myosin was unchanged (about 6.5 μg/mg wet weight). The results suggest that old age is not associated with pronounced changes in the cellular contractile and cytoskeletal proteins or in the mechanical properties of the contractile machinery. The age-related changes in mechanical properties previously reported for intact smooth muscle from urinary bladder are most likely due to alterations in the activation systems.
    Type of Medium: Electronic Resource
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