MICTURITION IN THORACIC SPINAL CORD INJURED CATS WITH AUTOGRAFTING OF THE ADRENAL MEDULLA TO THE SACRAL SPINAL CORD

Abstract

The role of noradrenergic projection from the pontine micturition center to the sacral spinal cord during micturition was examined in thoracic spinal cord injured cats after autografting the adrenal medulla to the sacral spinal cord. In 13 female cats the lower thoracic cord was transected and the right adrenal gland was removed under halothane anesthesia. The resected adrenal medulla was divided into several small pieces, which were subsequently autografted to the sacral spinal cord in 7 cats. Another 6 cats underwent sham operation and served as controls. Continuous cystometry and electromyography of the external urethral sphincter were performed every 2 weeks postoperatively without anesthesia. At week 8 the sacral spinal cord was removed and immunohistochemical testing was done to assess tyrosine hydroxylase immunoreactivity. At week 6 the relative mean duration of detrusor-external sphincter coordination plus or minus standard error during bladder contraction was 62.4% +/- 4.9% in adrenal grafted cats, which was significantly (p = 0.0485) longer than in controls (34.2% +/- 12.6%). However, maximum bladder contraction pressure, bladder contraction duration and post-void residual urine volume were not significantly different in the 2 groups. Tyrosine hydroxylase immunoreactive cells were observed in and on the sacral spinal cord in adrenal grafted animals but not in controls. Autografting the adrenal medulla to the sacral spinal cord prolonged detrusor-external sphincter coordination during bladder contraction in thoracic spinal cord injured cats, although other urodynamic parameters did not change. Therefore, noradrenergic projections to the sacral spinal cord may relax the external urethral sphincter during bladder contraction.