Changes of activity in lumbar preganglionic neurones during slow urinary bladder filling in the cat

The hypothesis was tested that sympathetic neurones projecting to the pelvic organs are excited during the collecting phase of the urinary bladder and inhibited when the intravesical pressure is beyond micturition threshold. Activity in single lumbar sympathetic preganglionic neurones projecting in the lumbar splanchnic nerves was measured when intravesical pressure was increased by slow filling at 2 ml/min in anaesthetized cats. Nine of 10 neurones tested were excited in a graded manner up to an intravesical pressure of 50 mmHg and during isovolumetric bladder contractions. On the basis of these quantitative results the hypothesis was refuted. The functional implications are discussed.