Wall mechanics of the rat bladder. II. Hydrodynamic studies in the frequency domain.

The hydrodynamic properties of the urinary bladder in rat were examined by means of very small periodic changes in volume at different frequencies. The elastance increased with increasing frequency of volume changes, indicating the presence of viscoelastic elements. When the bladder was only moderately distended the influence of viscosity was minor. We consider that the rat bladder examined by this technique is an ideal experimental model for assessment of in vivo effects of pharmacological agents on bladder wall tonus. For example, cholinergic treatment showed a 100% increase in elastance and atropine inhibited this effect completely within 3 min.