A possible role for urinary bladder epithelium in bradykinin-induced contraction in diabetic rats

Diabetes provokes a greater responsiveness of rat urinary bladder preparations to bradykinin and a greater formation and release of prostaglandin F2 alpha, without affecting prostaglandin E2 release significantly. Inhibition of cyclooxygenase by indomethacin (1 microM) inhibits the contraction elicited by bradykinin and leads to identical contractile responses of control and diabetic urinary bladder strips. Removal of the urinary bladder epithelium does not modify the contractile response evoked by bradykinin in control preparations but significantly decreases the contraction of preparations of diabetic tissues. Quantitatively, the activity of control urinary bladder strips with epithelium and the activity of diabetic preparations without epithelium are the same. More prostaglandin F2 alpha is released into the medium by urinary bladder strips devoid of epithelium in both control and in diabetic rats. These results indicate a role for epithelial cells in the smooth muscle contraction evoked by bradykinin in diabetic rats.