The integrative function of vagal nerves in urinary bladder activity in rats with and without intravesical noxious stimulation.

INTRODUCTION & OBJECTIVES: There is no evidence that vagal nerve innervate the urinary bladder. The aim of the study was to evaluate the effect of left vagal nerve dissection (LVND) on urinary bladder activity in normal rats and after intravesical noxious stimulation (INS).

MATERIAL & METHODS: Experiment was performed on 30 rats. All animals were divided into 4 groups--I: control rats (n = 12), II: rats after LVND without (INS) (n = 6), III: rats after INS without LVND (n = 6), IV: rats after LVND with INS (n = 6). Cystometry was performed under urethane anaesthesia. The INS was induced by continuously infusion of hypertonic saline (2080 mOsm/l) at a rate of 0.046 ml/min.

RESULTS

LVND induced an increase of basal-BP (+92%), threshold-TP (+21%), and maximal voiding pressure-MVP (+28%), as well as intercontraction intervals-ICI (+84%), functional bladder capacity-fBC (+87%), and compliance (+81%). INS induced detrusor overactivity (DO) characterised by a decrease of ICI (-51%) and fBC (-50%), and also an increase of BP (+118%), detrusor overactivity index-DOI (+413%) and motility index-MI (+33%). LVND diminished the severity of DO characterised by an increase of ICI (+86%), fBC (+84%), compliance (+62%), as well as a decrease of DOI (-50%) and MI (-18%).

CONCLUSIONS

The modulation of vagal nerve activity affect the urinary bladder function in naive conditions, as well as in case of INS (hyperosmolar). These data implies the integrative action of visceral vagal nerve innervation in urinary bladder function. However, further evaluations are strongly required in order to understand this action in various conditions.