Abstract
Objectives: To investigate the effect of warming on contraction of the detrusor muscle and the micturition reflex in rats.
Methods: Female Sprague-Dawley rats were used in this study. Changes in the contractile response of detrusor smooth muscle strips to 40 mM KCl caused by warming to 40°C and 42°C were evaluated by an isometric tension recording study. The effect of intravesical warming at 40.7±1.0°C on the micturition reflex was evaluated by continuous infusion cystometry in conscious rats.
Results: Warming to 40°C and 42°C inhibited 40 mM KCl-induced contractions of detrusor smooth muscle strips by 10% and 15.5%, respectively. Intravesical warming at 40.7±1.0°C decreased the pressure threshold for inducing micturition by 14%, resting pressure by 30%, closing peak pressure by 22%, 2nd phase contraction duration by 36%, bladder contraction duration by 26%, and increased bladder compliance by 17%. Maximal voiding pressure and 1st phase contraction duration were unaltered.
Conclusions: Our results demonstrated that warming relaxed the detrusor muscle and increased bladder compliance. This suggests that warming might be useful for treatment of low compliance bladder observed in the neurogenic bladder due to neurological diseases such as spinal cord injury. To clarify the usefulness of warming or hot springs for the treatment of neurogenic bladder, the effect of warming on the body surface on the micturition reflex should be investigated.
