PERFORMANCE ASSESSMENT AND VALIDATION OF AN ENHANCED 12-RAT METABOLIC CAGE EQUIPPED WITH A NOVEL 100-GRAM LOAD CELL SENSOR INTERFACE

Department

Biomedical Sciences

Document Type

Conference Presentation

Conference Title

Neurourology and Urodynamics

Location

Hyatt Regency Scottsdale Resort & Spa at Gainey Ranch Scottsdale, Arizona

Conference Dates

February 28 – March 4, 2017

Date of Presentation

2-1-2017

Journal ISSN

1520-6777

Journal Volume Number

36

Journal Issue Number

1

First Page

S19

Last Page

S19

Abstract

Introduction: The metabolic cage is an important noninvasive tool used to assess ambulatory voiding function in conscious rodents. Other standardized assessments of lower urinary tract (LUT) function in the rat include the 2-hour filter paper test and bladder cystometry, however these tests are labor intensive and represent a single point in time.We sought to validate our enhanced metabolic cage with a novel 12-channel load cell sensor interface, which allows for realtime automated assessment of LUT function. Methods: LUT function of female Sprague-Dawley rats were assessed at multiple time points with: A) two-hour filter paper test (n = 35, 129 samples), B) Metabolic cage (n = 35, 129 cage cycles) and C) Anesthetized bladder cystometry (n = 6). Twelve rats were simultaneously housed in metabolic cages (Tecniplast, Model 3701M081) during each cage cycle (18–24 hr). For the first two hours of each cage cycle, voided volume was measured using filter paper. Urine output for each animal was then measured using twelve 100-gramWheatstone bridge load cells connected to three 4-channel bridge amplifier USB transducers (Phidgets Inc., Model 1046) and data recorded continuously at one-second intervals (DSP Robotics, FlowBotics Studio v3.0.8). Anesthetized cystometry was then performed using urethane sedation (1.2 g/kg). Results: Load cell sensor performance was assessed using a micropipette which demonstrated accurate correlation with known droplet weight (sensitivity range 100–3,000 μL), as well as urine droplet weight after passing through both clean and dirty metabolic cages (sensitivity range 200–3,000 μL). The 2-hour filter paper test demonstrated voided urine droplet volumes which significantly correlated (Pearson r = 0.55, p < 0.001, alpha = 0.05) with daytime voided volumes obtained by metabolic cage. Voided volume demonstrated a non-significant (n = 6) positive correlation with cystometric mean voided volume (Pearson r = 0.48, p = 0.33, alpha = 0.05), and was consistently greater in ambulatory conscious rats (mean 1,014 μL, range 577–2,223) compared to anesthetized cystometry (mean 126 μL, range 20–211). Conclusion: Metabolic cage assessment of LUT function correlated with voided volumes using the filter paper test and anesthetized bladder cystometry. Rat bladder function and behavior patterns may be reliably assessed over time with our enhanced metabolic cage, without the need for anesthesia or terminal bladder cystometry. Funding Source: SUFU Foundation

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