LAUSR

episodes on lower urinary tract (LUT) function in naïve and SCI rats. METHODS: We assessed the effects of three single bout AIH protocols on bladder intravesical pressure (BP) and void volume recorded under urethane anesthesia (1.4 g/kg) in naïve and midthoracic moderate contusion SCI (4-week survival) rats during continuous infusion of saline (0.04 ml/min) into the bladder to elicit rMEs. The AIH protocols implemented consisted of alternating exposures of hypoxia (12% O2) and normoxia using the following: (1) three 5-min episodes, (2) five 3-min episodes, and (3) ten 1.5-min episodes. Following the AIH exposure, data acquisition continued for up to 120 minutes while the rats continued to breathe room air. RESULTS: In both naïve and SCI rats, each single bout AIH protocol produced a comparable decrease in rME frequency and increase in void volume that persisted for up 120 min post-AIH. Moreover, in SCI rats, each of the protocols was equally effective in reducing the ratio of nonvoiding/voiding bladder contractions. Single bout AIH exposure also produced transient increases in both bladder contraction threshold BP and minimum BP. Modulation of LUT behavior during individual exposures to hypoxia and immediately following each hypoxic episode (“off effect”) were also observed, with the intensity of the “off effect” tending to be lower following short duration (e.g., 10 x 1.5-min) hypoxic exposures. CONCLUSIONS: Our observations suggest that while each single bout AIH protocol is effective in improving micturition and reducing non-voiding bladder contractions in SCI rats, subtle differences in magnitude and/or timing were noted across the protocols.