Gastrointestinal Motility Monitor (GIMM)

Abstract

The Gastrointestinal Motility Monitor (GIMM; Catamount Research and Development; St. Albans, VT) is an in vitro system that monitors propulsive motility in isolated segments of guinea pig distal colon. The complete system consists of a computer, video camera, illuminated organ bath, peristaltic and heated water bath circulating pumps, and custom GIMM software to record and analyze data. Compared with traditional methods of monitoring colonic peristalsis, the GIMM system allows for continuous, quantitative evaluation of motility. The guinea pig distal colon is bathed in warmed, oxygenated Krebs solution, and fecal pellets inserted in the oral end are propelled along the segment of colon at a rate of about 2 mm/sec. Movies of the fecal pellet proceeding along the segment are captured, and the GIMM software can be used track the progress of the fecal pellet. Rates of propulsive motility can be obtained for the entire segment or for any particular region of interest. In addition to analysis of bolus-induced motility patterns, spatiotemporal maps can be constructed from captured video segments to assess spontaneous motor activity patterns. Applications of this system include pharmacological evaluation of the effects of receptor agonists and antagonists on propulsive motility, as well as assessment of changes that result from pathophysiological conditions, such as inflammation or stress. The guinea pig distal colon propulsive motility assay, using the GIMM system, is straightforward and simple to learn, and it provides a reliable and reproducible method of assessing propulsive motility. Video LinkThe video component of this article can be found at https://www.jove.com/video/2435/ Protocol Preparation of Colon Tissue for GIMM1. To prepare a segment of distal colon for the Gastrointestinal Motility Monitor (GIMM), first place the isolated colon in ice-cold Krebs solution (121 mM NaCl, 5.9 mM KCl, 2.5 mM CaCl 2 , 1.2 mM MgCl 2 , 25 mM NaHCO 3 , 1.2 mM NaH 2 PO 4 , and 8 mM glucose; aerated with 95% O 2 /5%CO 2 ). Clear away remaining mesentery from the outer wall and make a small incision in the oral end so it can be distinguished when placed into the organ bath. Note: tissue may remain in iced Krebs solution for up to 2 hours prior to experimentation. 2. Next, position the inflow and outflow conduits in the organ bath so they are outside of the camera field to prevent interference with the image acquisition. Continuously perfuse the organ bath with prewarmed (37°C) oxygenated (95%, 5% CO 2 ) Kreb's solution at a flow rate of 10 ml/ min. 3. Keeping track of the oral vs. anal ends, pin a segment of distal colon (at least 5 cm) on either end in the organ bath, allowing a small degree of laxity so that the segment can move freely up to 1 cm in the middle. The oral end should be positioned towards the researcher for ease of placing the fecal pellet. Colonic segments should be pinned in the same manner by the same researcher for every experiment within a given set of experiments because the length and tension of the s...

Spatiotemporal Mapping of Motility in <em>Ex Vivo</em> Preparations of the Intestines

“…Spatiotemporal maps made from these video records are designed to represent the movement of the whole segment as described above. In contrast, in the mid-to distal colon where the contents are more solid, activity is initiated by insertion of a fecal pellet (epoxy coated natural pellet or artificial pellet) and spatiotemporal maps are designed to reflect the movement of the pellet through the colon as illustrated in the JOVE article of Hoffman et al 13 . Thus the setup of the experiment and analysis are crucial and depend upon the type of stimulus and the region being studied.…”

“…While many groups have generated their own software packages or plugins, they all analyze diameters of a tissue segment and convert those various diameters to grayscale representation. A commercially available recording and analysis system called the GastroIntestinal Motility Monitoring system (GIMM) provides a turnkey approach that allows for analysis of both propulsive motility via fecal pellet velocity determination in the guinea pig distal colon 13 as well as analysis of propulsive and mixing motility patterns with a fluid stimulus in intact intestinal segments 4,5,[14][15][16][17][18][19] 4. General Experimental Procedures 1.…”

Analysis of spatiotemporal pattern and quantification of gastrointestinal slow waves caused by anticholinergic drugs

“…Studies recommend not pinning the organ until it is completely taut, as this inhibits contraction. 49,69 However, since the program analyses a cross-section and measures the change in diameter, if there is too much movement it could be analyzing instead the oscillation of adjacent cross-sections of the organ. A possible method to include this would be installing a tracking system where movement of the organ could be monitored, and negated during analysis.…”

“…It was suggested that for analysis, the settings were adjusted to high contrast between the organ and background. 49 This required heightening the contrast, and increasing the exposure and brightness. Any markings or debris within the camera viewfinder would create artifacts and noise in the spatiotemporal map.…”

“…The system comprises the organ bath, video camera, circulating pumps, associated tubing and heating systems, and was set up in accordance to the recommended instruction manual. 49 The Krebs solution is heated to 37 C, and carbogen gas (95% oxygen and 5% carbon dioxide), is aerated through the solution which circulates to the organ.…”