Experimental model of bladder outflow tract obstruction in the guinea-pig.

Bladder outflow tract obstruction was produced in immature female guinea-pigs. Obstruction caused an increase in voiding pressure and bladder weight and a decrease in bladder compliance. No change occurred in the sensitivity of obstructed detrusor strips to exogenous agonists, but the force of contraction and response to electrical stimulation of the intrinsic nerves were less than in the strips from controls. The response of strips from sham-operated animals to exogenous agonists and to electrical stimulation was greater than that from obstructed animals. The effects of length and tension could not account for the in vitro responses from obstructed animals. Histology after obstruction showed muscle hypertrophy, connective tissue infiltration and decrease in nerve density. Many of the changes resembled those seen in the obstructed human bladder.