Purpose: We investigated the effects of the combination of bladder outlet obstruction and diabetes mellitus on in vitro rat bladder body strip function.
Materials and methods: Longitudinal strips were removed from ventral and dorsal detrusor of age matched control, 2-week diabetic, 2-week obstructed and 2-week obstructed diabetic rats. Contractile responses to electrical field stimulation, carbachol, adenosine triphosphate, KCl and phenylephrine, and relaxations in response to norepinephrine and isoproterenol were measured.
Results: Bladders from diabetic, obstructed and obstructed diabetic rats were 1.6-fold, 2.6-fold and 3.6-fold heavier than those from controls. Responses of bladder strips from diabetics to all stimuli were similar to those of controls. Strips from obstructed rats were significantly less responsive to norepinephrine than those from controls or diabetics and strips from obstructed diabetics were significantly less responsive to norepinephrine and isoproterenol than those from all other groups. Strips from obstructed diabetics had significantly decreased responses to field stimulation, while responses to carbachol were decreased to a lesser extent. Responses of strips from obstructed rats to field stimulation were also decreased compared with controls but were significantly greater than those of the obstructed diabetic group. Responses to adenosine triphosphate, KCl and phenylephrine were similar in all groups.
Conclusions: The combination of outlet obstruction and diabetes mellitus causes significant increases in bladder mass compared with either diabetes or obstruction alone. Bladder strips from obstructed diabetics show characteristics of denervation accompanied by alterations in beta-adrenergic function, suggesting that the coexistence of outlet obstruction and diabetes increases the rate of development of bladder decompensation.