The bladder (muscle) has to contract while the external urethral sphincter (valve) has to open. This simultaneous action is required for the natural expulsion of the bladder to occur.
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, 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.