title: Functional and biochemical characteristics of urinary bladder muscarinic receptors in long-term alloxan diabetic rats.
abstract: OBJECTIVE
  To re-examine the function of the urinary bladder in vivoas well as to determine the functional and biochemical characteristics of bladder muscarinic receptors in long-term alloxan-induced diabetes rats.
  
  
  METHODS
  Two-month-old male Wistar rats were injected with alloxan and the animals showing blood glucose levels >300mg/dL together with age-paired untreated animals were kept for 11 months. Body weight, bladder weight, blood glucose, and urinary volume over a period of 24 hours were determined in both groups of animals. A voiding cystometry in conscious control and diabetic rats was performed to determine maximal micturition pressure, micturition contraction interval and duration as well as voided and post-voiding residual volume. In addition, concentration-response curves for bethanechol in isolated bladder strips, as well as [3H]-N methyl-scopolamine binding site characteristics in bladder homogenates were determined.
  
  
  RESULTS
  Mean bladder weight was 162.5±21.2mg versus 290±37.9mg in control and treated animals, respectively (p<0.05). Micturition contraction amplitude (34.6±4.7mmHg versus 49.6±2.5mmHg), duration (14.5±1.7 seconds versus 23.33±4.6 seconds) and interval (87.5±17.02 seconds versus 281.11±20.24 seconds) were significantly greater in alloxan diabetic rats. Voided urine volume per micturition contraction was also significantly higher in diabetic animals. However the post-voiding residual volume was not statistically different. Bethanechol potency (EC50 3µM versus 5µM) and maximal effect (31.2±5.9g/g versus 36.1±6.8g/g) in isolated bladder strips as well as number (169±4fmol/mg versus 176±3fmol/mg protein) and affinity (0.69±0.1nM versus 0.57±0.1nM) of bladder muscarinic receptors were also not statistically different.
  
  
  CONCLUSIONS
  Bladder function in vivo is altered in chronic alloxan-induced diabetes rats without changes in functional and biochemical characteristics of bladder muscarinic receptors.
authors.affiliation: Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Jeová Nina
authors.initials: JN
authors.lastname: Rocha
mesh_terms: D000496:Alloxan / Q000008:administration & dosage; D000818:Animals; D018723:Bethanechol / Q000008:administration & dosage; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000378:metabolism*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D019832:N-Methylscopolamine / Q000008:administration & dosage; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D014554:Urination / Q000187:drug effects / Q000502:physiology
chemical_list: D011976:Receptors, Muscarinic; D018723:Bethanechol; D000496:Alloxan; D019832:N-Methylscopolamine