Voltage-dependent potassium currents of urethral afferent neurons in diabetes mellitus.

Urethra-to-bladder and urethra-to-urethra reflexes appear to be important for coordination of proper voiding. Diabetes mellitus (DM) is known to result in afferent neuropathy. Neuropathic alterations in electrophysiological properties of urethral afferent neurons may therefore contribute to voiding dysfunction seen in diabetes mellitus. Accordingly, we studied urethral afferent neuronal somata in streptozotocin-induced DM or age-matched vehicle controls by whole-cell patch clamp at 5- or 10-week time points. One week prior to study, Fast Blue was injected into the proximal urethra to label urethral afferent neurons. A previously undescribed diminution of afferent neuronal voltage-dependent potassium currents was a prominent feature of urethral afferent neuropathy in DM, acting to increase neuronal excitability. Thus, unlike bladder afferent neurons, urethral afferent neurons may be hyperexcitable well into DM progression.