The Suitability of Propofol Compared with Urethane for Anesthesia during Urodynamic Studies in Rats

Urethane anesthesia preserves many reflex functions and is often the preferred anesthetic for urodynamic studies in rats. Because of the toxicity profile of urethane, its use as an anesthetic typically is limited to acute and terminal investigations. Alternative anesthetic options are needed for longitudinal studies of micturition reflexes in rats. In this study, we evaluated propofol anesthesia administered at constant rate infusion at different planes of anesthesia in rats for combined cystometrography and external urethral sphincter (EUS) EMG in rats. No reflex micturition was noted after rats received 100%, 80%, or 60% of a previously reported anesthetic dose of propofol. At 40% of the standard propofol dose, a subset of rats showed reflex voiding, with bladder contractions and associated EUS EMG activity. In contrast, urethane anesthesia at a surgical plane allowed for reflex voiding with bladder contractions and EUS activation. Latency to leaking or voiding was longer in rats under propofol anesthesia than in those under urethane anesthesia. In a subset of rats with reflex voiding under propofol anesthesia, voiding efficiency was decreased compared with that of rats anesthetized with urethane. We conclude that propofol anesthesia suppresses micturition reflexes in rats more efficiently than did urethane. Propofol is a suitable anesthetic for longitudinal studies in rats, but its use for urodynamic evaluations is limited in these animals due to its marked suppression of both bladder contractions and EUS EMG activation.