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  • 1
    ISSN: 1434-0879
    Keywords: Key words Endothelin receptors ; Nitric oxide synthase ; Rabbit ; Bladder obstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Bladder outlet obstruction (BOO) is associated with altered bladder structure and function. Endothelin-1 (ET-1) has mitogenic and potent contractile properties. There are two ET receptors: ETA and ETB. Nitric oxide synthase (NOS) is the enzyme responsible for the synthesis of nitric oxide (NO) which is involved in smooth muscle relaxation. We investigated whether there are any changes in the density of ET-receptors and NOS in the detrusor and bladder neck in a rabbit model of BOO. Partial BOO was induced in adult male New Zealand White rabbits. Sham operated age-matched rabbits acted as controls. After six weeks the urinary bladders were excised and detrusor and bladder neck sections incubated with radioligands for ET-1, ETA and ETB receptors and with [3H]–l-NOARG (a ligand for NOS). NADPH histochemistry was also performed. BOO bladder weights were significantly increased (P=0.002). ET-1 binding and ETA receptor binding sites were significantly increased in the BOO detrusor smooth muscle (P=0.04, P=0.03 respectively) and urothelium (P=0.002, P=0.02 respectively). ETB receptor binding sites were also significantly increased in the BOO detrusor smooth muscle (P=0.04). However, there was no change in the BOO bladder neck. NOS was significantly decreased in the detrusor smooth muscle (P=0.003) and urothelium (P=0.0002). In the bladder neck NOS was also significantly reduced in the urothelium (P=0.003). NADPH staining was decreased in the detrusor and bladder neck. The up-regulation of ET receptors along with the down-regulation of NOS in the detrusor may contribute to the symptoms associated with BOO. Since ET-1 has a mitogenic role, especially via its ETA receptors, the increase in ETA receptors may also be involved in detrusor hyperplasia and hypertrophy in BOO. ET antagonists may therefore have a role in the treatment of patients with BOO.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-0879
    Keywords: Key words Endothelin-1 ; Rabbit ; Bladder ; Diabetes mellitus ; Smooth muscle cell proliferation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Urinary bladder hypertrophy and hyperplasia are well recognised in diabetic cystopathy. The urinary bladder is known to synthesise endothelin-1 (ET-1), a potent vasoconstrictor peptide with mitogenic properties. Using diabetic New Zealand White (NZW) rabbits, we investigated the potential role of ET receptor subtypes (ETA and ETB) on the proliferation of bladder smooth muscle cells (SMC). Diabetes mellitus was induced in adult male NZW rabbits. After 6 months, control (n=6) and diabetic (n=6) bladders were removed and SMC from the dome and bladder neck were grown using standard explant methodology. At passage two, the cells were made quiescent and then further incubated in foetal calf serum (FCS), control age-matched rabbit serum (CRS) or diabetic rabbit serum (DRS) in the presence or absence of ETA-antagonist (BQ123) or ETB-antagonist (BQ788). SMC proliferation was then measured with 5-bromo-2′deoxy-uracil 24 h later and by cell counting (using a haemocytometer) at 48 h. Neither BQ123 nor BQ788 influenced detrusor or bladder neck SMC proliferation in FCS or CRS. However, in the presence of DRS, BQ123 and BQ788 significantly inhibited diabetic detrusor and bladder neck SMC proliferation at 30 and 100 nmol/l (P 〈 0.03 and P 〈 0.01, respectively). Cell counts were also significantly reduced from the diabetic detrusor and bladder neck (P 〈 0.01 and P 〈 0.03 with BQ123 and BQ788, respectively). These results suggest that ET may play a pathophysiological role in the bladder SMC hyperplasia associated with diabetes mellitus.
    Type of Medium: Electronic Resource
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