Objective: To explore a myogenic basis of the spontaneous contractions on the rat bladder smooth muscle strip in a detrusor instability (DI) model in vitro, and to study a nerve blockers cocktail affecting the spontaneous contractions as well as electrical stimulated contractile response. Methods: DI model rats were made by partial bladder outlet obstruction (BOO) and confirmed by the filling cystometry. Detrusor strip was dissected from fresh bladder, fixed for an isometric tension trial. The contractions were recorded during electrical stimulation or exposure to some agents. Results: The cocktail diminished the nerve-mediated contractile response effectively in DI preparation. DIs spontaneous contractions remained during the presence of the cocktail with a significant change in its contractile amplitude. Conclusion: With the local nerve-concerned factors abolishment by the cocktail, the DI bladder preparations still have the spontaneous contractions, indicating a myogenic basis from themselves.