[Denervation supersensitivity of the detrusor muscle due to bladder overdistension, with special reference to the relationship between supersensitivity, and changes in the connective tissue].

To investigate denervation supersensitivity of the detrusor muscle due to prolonged bladder overdistension, overdistended bladders were produced in female mongrel dogs by bladder neck obstruction for 48 hours and the dogs were sacrified 1, 2 and 4 weeks after overdistension. The sensitivity of the detrusor muscle to acetylcholine was measured using the isometric in vitro technique. The bladder wall tissues were examined with Masson's trichrome staining. The blood flow of the bladder wall was determined by the hydrogen gas clearance method. Sensitivity reached a maximum 2 weeks after overdistension, thereafter decreasing to a lower level 4 weeks after overdistension than that of the untreated detrusor muscle. A decrease of blood supply to the bladder wall, the rate being 63% immediately after overdistension, may result in a degeneration of the axon which is more fragile to ischemic changes. Subsequently axonal degeneration may be followed by denervation supersensitivity of the detrusor muscle. Remarkable fibrotic changes of the bladder wall 4 weeks after overdistension suggested a decrease of the detrusor muscle contraction to acetylcholine.