Contractile effect and tissue content of arginine vasopressin in the urinary bladder of Brattleboro rats with hereditary diabetes insipidus.

1. Urinary bladders from male rats of the Brattleboro strain with hereditary diabetes insipidus (DI) were analyzed for presence of immunoreactive arginine vasopressin (ir-AVP). Healthy rats were used as controls. 2. Bladders from the DI rats were heavier than controls. Concentration of ir-AVP was lower in DI bladders, but total amount of ir-AVP was similar to that in controls. 3. EC50 values for the AVP concentration-response relations were similar for control and DI bladder strips. Maximum response to AVP relative to response to K+ high solution was lower in the DI group. 4. An AVP receptor antagonist that significantly blocked response to exogenous AVP had no effect on response to field stimulation. 5. We suggest that AVP is synthetized locally and that AVP is not the non-adrenergic non-cholinergic transmitter responsible for the atropine resistant contraction in rat bladder.