Long-term recording of external urethral sphincter EMG activity in unanesthetized, unrestrained rats.

TitleLong-term recording of external urethral sphincter EMG activity in unanesthetized, unrestrained rats.
Publication TypeJournal Article
Year of Publication2014
AuthorsLaPallo, BK, Wolpaw, J, Chen, XY, Carp, JS
JournalAm J Physiol Renal Physiol
Date Published08/2014
KeywordsAnimals, Electrodes, Implanted, Electromyography, Female, Pubic Bone, Rats, Rats, Sprague-Dawley, Urethra, Urination, Urodynamics

The external urethral sphincter muscle (EUS) plays an important role in urinary function and often contributes to urinary dysfunction. EUS study would benefit from methodology for longitudinal recording of electromyographic activity (EMG) in unanesthetized animals, but this muscle is a poor substrate for chronic intramuscular electrodes, and thus the required methodology has not been available. We describe a method for long-term recording of EUS EMG by implantation of fine wires adjacent to the EUS that are secured to the pubic bone. Wires pass subcutaneously to a skull-mounted plug and connect to the recording apparatus by a flexible cable attached to a commutator. A force transducer-mounted cup under a metabolic cage collected urine, allowing recording of EUS EMG and voided urine weight without anesthesia or restraint. Implant durability permitted EUS EMG recording during repeated (up to 3 times weekly) 24-h sessions for more than 8 wk. EMG and voiding properties were stable over weeks 2-8. The degree of EUS phasic activity (bursting) during voiding was highly variable, with an average of 25% of voids not exhibiting bursting. Electrode implantation adjacent to the EUS yielded stable EMG recordings over extended periods and eliminated the confounding effects of anesthesia, physical restraint, and the potential for dislodgment of the chronically implanted intramuscular electrodes. These results show that micturition in unanesthetized, unrestrained rats is usually, but not always, associated with EUS bursting. This methodology is applicable to studying EUS behavior during progression of gradually evolving disease and injury models and in response to therapeutic interventions.

Alternate JournalAm. J. Physiol. Renal Physiol.
PubMed ID24990895
PubMed Central IDPMC4137128
Grant ListHD36020 / HD / NICHD NIH HHS / United States
NS061823 / NS / NINDS NIH HHS / United States
NS22189 / NS / NINDS NIH HHS / United States
P41 EB018783 / EB / NIBIB NIH HHS / United States
R01 EB000856 / EB / NIBIB NIH HHS / United States
R01 NS022189 / NS / NINDS NIH HHS / United States

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