The RIRC Welcomes New Faculty Member - Dr. Harriet Chang
Dr. Chang has been working in the urological fields for over 10 years. Her predoctoral training was with Dr. William C. de Groat, who is recognized as one of the world leaders in research on neural control of bladder function. Dr. de Groat received the Reeve-Irvine Research medal in 2009 for his fundamental studies in this area. Dr. Chang’s expertise is in pharmacological modulation of bladder function following spinal cord injury (SCI). Her studies focus on rodent models, and the control of a muscle called the external urethral sphincter. To void the bladder in a normal way requires that two physiological actions occur simultaneously. The bladder (which is actually a muscle) has to contract and at the same time, the external urethral sphincter, which is basically a biological valve e, has to open. These two actions have to occur in “synergy” (which means together). People who have suffered a spinal cord injury often suffer from a condition called “dys-synergia”, in which there is bladder contraction triggered by a full bladder at the same time that the sphincter (the valve) doesn’t open. This causes a pathological increase in pressure within the bladder, which pushes urine back up into the kidneys. All of this greatly increases the chances for kidney damage and urinary tract infections. Thus, figuring out how to control the external urethral sphincter is of great importance.
Dr. Chang is currently funded by NIH/NIDDK to investigate the urethral function by using spinal cord epidural stimulation (SCS) in the rodent model of SCI. SCS is a well-developed and widely used technique on neuromodulation, especially for neuropathic pain and the recent studies of locomotion. Dr. Chang first used this technique on modulation of urethral sphincter focusing on the improvements of voiding function in rodents with SCI.
The use of SCS over the upper lumbar cord (L3) evokes the urethral relaxation (Figure 1). This technique improves the voiding efficiency and promotes urine expulsion in the rodents with dys-synergia after SCI.
Dr. Chang’s team also applies L3/SCS to investigate the effect on bladder overactivity in rodents. Overactive bladders (OAB) has the symptoms including frequent bladder contractions, urgency and urine leakage, commonly seen in people over 40 years old and men with prostate enlargement. L3/SCS increases the bladder capacity and decrease the bladder contractions (Figure 2).
Dr. Chang wishes to establish the foundation for studies of mechanisms associated with bladder dysfunction and contributes to improve voiding efficiency. Dr. Chang will explore new therapeutic approaches to these problems using pharmacological modulation and artificial electrical stimulation.
