A study on the viscoelastic properties of the urinary bladder in dogs

This experimental study was designed and carried out in order to investigate the participation of the collagen and muscular tissues on the viscoelastic properties of the bladder wall. Sixty-five adult male mongrel dogs were utilized. These animals were divided into 5 groups: control group (n = 10); dogs (n = 10) receiving 2.5 mg/kg atropine (cholinergic antagonist); dogs (n = 10) receiving 0.7 mg/kg verapamil (calcium extracellular inflow blocker); dogs (n = 10) receiving 0.1 mg/kg/min nitroprusside (intracellular calcium blocker), and dogs (n = 25) receiving EGTA (a calcium-chelating agent) at increasing doses from 90 to 450 mg/kg. Based on a mathematical model, we have demonstrated that: (1) the collagen component is responsible for the elastic properties; (2) the muscle component is responsible for the viscoelastic properties; (3) the viscoelastic properties have an active element which is affected by calcium total depletion, and (4) such viscoelastic properties are not dependent on cholinergic stimulation.