Bajzer Ž, Gibbons SJ, Coleman HD, Linden DR, Farrugia G. A gamma variate model that includes stretched exponential is a better fit for gastric emptying data from mice. Am J Physiol Gastrointest Liver Physiol 309: G162-G170, 2015. First published June 4, 2015; doi:10.1152/ajpgi.00280.2014.-Noninvasive breath tests for gastric emptying are important techniques for understanding the changes in gastric motility that occur in disease or in response to drugs. Mice are often used as an animal model; however, the gamma variate model currently used for data analysis does not always fit the data appropriately. The aim of this study was to determine appropriate mathematical models to better fit mouse gastric emptying data including when two peaks are present in the gastric emptying curve. We fitted 175 gastric emptying data sets with two standard models (gamma variate and power exponential), with a gamma variate model that includes stretched exponential and with a proposed two-component model. The appropriateness of the fit was assessed by the Akaike Information Criterion. We found that extension of the gamma variate model to include a stretched exponential improves the fit, which allows for a better estimation of T 1/2 and Tlag. When two distinct peaks in gastric emptying are present, a two-component model is required for the most appropriate fit. We conclude that use of a stretched exponential gamma variate model and when appropriate a two-component model will result in a better estimate of physiologically relevant parameters when analyzing mouse gastric emptying data. motility; smooth muscle; gastrointestinal tract; empirical mathematical models THE MEASUREMENT OF GASTRIC emptying in human subjects and animal models of disease is an important technique for understanding the changes in gastric motility that occur under normal physiological conditions, in disease, or in response to drugs. Acute physiological changes in gastric emptying can be identified in response to the content and nature of a meal including the effects of calories, osmolarity, lipid, protein, and carbohydrate content (9). Determination of gastric emptying has clinical relevance since the delay of gastric emptying of solids is required for positive diagnosis of gastroparesis. Gastroparesis can occur secondary to drugs or systemic disease as a complication of diabetes or remain idiopathic (21). Accelerated gastric emptying is also observed in subsets of patients with symptoms suggestive of functional dyspepsia, or dumping, as well as in a subset of patients with diabetes particularly early after diagnosis (12,25). Accelerated gastric emptying is also observed in animal models of diabetes (7). Prokinetic agents have been identified and studied by using gastric emptying tests in experimental animals and candidate drugs have been tested for unwanted effects on gastric emptying (24).Several noninvasive tests have been developed to follow gastric emptying in humans including scintigraphy and breath tests (5, 29), and some of these tests have been applied for ...