SUPERSENSITIVITY OF THE URINARY BLADDER TO ACETYLCHOLINE AND PROSTAGLANDINS IN DENERVATED RATS

Abstract

Using isometric in vitro technique, the sensitivity to acetylcholine and prostaglandins was studied in rats denervated by injecting 10% phenolglycerin into a subarachnoidal space between the 5th and 6th lumbar vertebrae, 1 to 28 days after injection.
The amplitude of spontaneous contractions of strips prepared from the bladders significantly increased 3 to 28 days after denervation as compared with those of control rats. The increase of the spontaneous contractions in rats 3 to 7 days after denervation was larger than that in rats 14 to 28 days after denervation.
An increase of contraction response to acetylcholine was observed from 3 days after denervation and reached a maximum level 7 days after denervation. This level remained for the period from 14 to 28 days after denervation.
Prostaglandin E₂ and F_2α induced the small contractions in control strips. The increase of contraction response to prostaglandins was observed 7 to 28 days after denervation. The increase of contraction response to prostaglandin E₂ was not observed 4 days after denervation.
These results suggested that supersensitivity of the bladder in denervated rats to acetylcholine mainly occurred through a pre junctional mechanisms at an early stage of denervation, however, through a post junctional mechanism at a later stage covering 7 to 28 days after denervation.