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1 Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
2 Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
3 Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States; Pittsburgh, Pennsylvania, United States
4 University of Pittsburgh; Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
* To whom correspondence should be addressed. E-mail: cftai{at}pitt.edu.
This study revealed that in awake chronic spinal cord injured (SCI) cats reflexes from perigenital skin area to the bladder can be either inhibitory or excitatory. Electrical perigenital stimulation at frequencies between 5 Hz and 7 Hz significantly inhibited large amplitude rhythmic reflex bladder activity; whereas frequencies between 20 Hz and 40 Hz induced large amplitude bladder contractions even at low bladder volumes when reflex bladder activity was absent. Both inhibitory and excitatory effects were enhanced as the stimulation intensity increased (5-30 V, 0.2 ms pulse width). During cystometrograms the inhibitory stimulation (7 Hz) significantly increased the micturition volume threshold 35±13% above the control volume, while the excitatory stimulation (30 Hz) significantly reduced the threshold 21±3%. Mechanical perigenital stimulation applied by repeatedly light stroking the perigenital skin with a cotton swab only induced an excitatory effect on the bladder. Both electrical and mechanical perigenital stimuli induced large amplitude (greater than 30 cmH2O) bladder contractions that were relatively consistent over a range of bladder volumes (10%-90% of the capacity). However, the excitatory electrical stimulation only induced bladder contractions lasting on average 42.2±3.9 seconds, but the mechanical stimulation induced bladder contractions that lasted as long as the stimulation continued (2-3 minutes). Excitatory electrical or mechanical perigenital stimulation also induced post-stimulus voiding. The ability to either inhibit or excite the bladder by non-invasive methods could significantly transform the current clinical management of bladder function after SCI.
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J. P. Woock, P. B. Yoo, and W. M. Grill Activation and inhibition of the micturition reflex by penile afferents in the cat Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2008; 294(6): R1880 - R1889. [Abstract] [Full Text] [PDF] |
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