Electric field stimulation alters the outputs of prostaglandins from isolated rat urinary bladder preparations. Influences of papaverine and tetradotoxin

The effects of electric field stimulation (EFS) on the outputs of prostaglandins (PGs) E₁, E₂ and F_2α from isolated contracting rat urinary bladders, were explored. Also, the influences of papaverine (5.10^-6 M) and of tetradotoxin (TTX = 5.10^-7 M) on PGs released by spontaneously contracting or electrically driven preparations, were tested. The basal control outputs of the three PGs in spontaneously contracting urinary bladders, had a comparable magnitude. On the contrary, in electrically stimulated preparations the output of PGE₂ rose significantly; that of PGF_2α presented a significant reduction and the release of PGE₁ was similar to that in controls. Papaverine failed to modify the profile of basal control PG release in non-stimulated bladders, abolished contractile responses to EFS and blocked the augmented output of PGE₂ elicited by EFS. The presence of TTX in the suspending solution had no action on the basal control release of PGs from non-stimulated spontaneously contracting preparations, depressed between 80-90% the inotropic responses triggered by EFS and completely antagonized the enhanced output of PGE₂ evoked by EFS. Results are discussed in terms of the relative participations of the evoked inotropism of the detrusor muscle or by the stimulation of nerve endings, accounting for the greater release of tissue PGE₂ after EFS.