velocity was measured to be 9.61 ± 1.97 mm/s (EGG) and 10.12 ± 2.68 mm/s (MGG). In the diseased state, SW parameters were found to be either brady- or tachyarrhythmic with a predominance of the former over the latter. The DF values found in the abnormal state were 1.22 ± 1.04 cpm (EGG) and 1.38 ± 1.17 cpm (MGG). While SWs could be easily identified visually from serosal recordings, this was not the case for cutaneous recordings due to the poor S/N ratio associated with the latter method. In conclusion, the qualitative and quantitative agreement between our EGG and our MGG results suggests that MGG is a promising method for the noninvasive study of GI electrophysiology. T1350 Simple and Noninvasive Breath Test: Evaluation of Prokinetic Drugs On Gastric Emptying in the Conscious Rats Masayuki Uchida, Kimiko Shimizu Background: Radioscintigraphy is generally accepted as the gold standard for measuring gastric emptying in humans. Recently 13 C-Breath test has been used clinically to evaluate gastric emptying. However, this method has not been validated enough in experimental animals. Aim: The present study aimed to establish a simple and noninvasive 13 C-breath test system in conscious rats. We tested the effects of prokinetic drugs affecting gastric emptying by using this system. Methods: Sprague-Dawley male rats were used. The animals were fasted in mesh cages for 18 h before each experiment in order to prevent coprophagy, but were allowed free access to drinking water during this period. Rats were orally adminis- tered Racol containing [1- 13 C]acetic acid and housed in a desiccator. The expired air in the desiccator was collected in a breath-sampling bag using a tube and aspiration pump. The level of 13 CO 2 in the expired air was measured using an infrared spectrometer (UBiT-IR300) at appropriate intervals for 120 min. The effects of dose and test meal volume were tested. Metoclopramide and mosapride were suspended 1% gum arabic solution and administered orally 30 min before Racol treatment. Atropine sulfate was dissolved in saline and adminis- tered subcutaneously 20 min before Racol treatment. In the control rats, 1% gum arabic solution or saline was treated. Results: During this period, 13 CO 2 excretion increased, peaked and decreased thereafter. The maximum concentration (Cmax) and area under the curve (AUC120min) of 13 CO 2 excretion increased in volume- and dose-dependent manners. The time taken to reach the maximum concentration (Tmax) of 13 CO 2 excretion delayed as the volume increased, but was not affected by the dose of 13 C-labeled acetic acid. Metoclopramide dose-dependently increased Cmax value, and shortened Tmax of 13 CO 2 excretion as com- pared with those of the control rats, whereas the AUC120min was not affected. Mosapride also increased Cmax value, and shortened Tmax of 13 CO 2 excretion as compared with those of the control rats, whereas the AUC120min was not affected. On the contrary, atropine sulfate dose-dependently decreased the Cmax and delayed Tmax of 13 CO 2 excretion as compared with those of the control rats, whereas the AUC120min was not affected. Conclu- sion: These results confirm that this simple method can successfully evaluate gastric emptying and prokinetic drugs. T1351 Modulation of Individual Components of the Distal Gastric Motor Response to Duodenal Glucose Infusion in Healthy Humans Laura Bryant, Carly M. Burgstad, Adam Deane, Marianne Chapman, Richard H. Holloway, Michael Horowitz, Robert Fraser Nutrient-mediated small intestinal feedback is important for the regulation of gastric empty- ing, and modulates antral, pyloric and duodenal motility. However, the relative nutrient loads at which individual components of this response are activated is unknown. Aim: To examine the sensitivity of individual components of the antro-pyloro-duodenal (APD) motor response to graded small intestinal glucose infusions in healthy humans. Methods: APD manometry was performed in 10 healthy subjects (8M; 48 ± 6 yrs; BMI 29.9 ± 1.7 kg/m 2 ) during four 20-min intraduodenal infusions of glucose at 0, 0.5, 1.0 and 1.5 kcal/min, in a randomised double-blinded fashion. Glucose solutions were infused at a rate of 1ml/min and separated by 40-min ‘wash-out' period. Blood glucose levels (BSL) were measured every 20-min. Data are mean ± SEM, comparison by ANOVA. Results: During fasting, antral wave frequency was 12.3 ± 2.3 waves/20 min (see figure), which was reduced in a dose-dependent fashion during glucose infusion (P=0.001) with a threshold at 0.5 kcal/min (P<0.05). The frequency of isolated pyloric pressure waves during fasting was 8.6 ± 1.9 waves/20min, which increased dose-dependently during glucose infusion (P<0.0001), with a threshold at 1.0 kcal/min (P<0.05). The total number of duodenal waves during fasting was 20.7 ± 2.4 waves/20min, which increased during the 1.5 kcal/min infusion (P<0.05). Fasting BSL was 5.7 ± 0.5 mmol/L and there were no differences in BSL following glucose infusion between caloric loads. Conclusion: There is a hierarchy for the activation of gastrointestinal motor responses to duodenal glucose infusion. This involves an initial suppression of the antrum, followed by pyloric stimulation and finally increased duodenal motility. The ability to generate a graded response may provide a mechanism to modulate gastric emptying rates according to the level of small intestinal receptor stimulation. A-537 AGA Abstracts T1352 Gastroparesis Hospitalizations in the US: Non-Diabetic Gastroparesis Is a Distinct and More Serious Health Problem Than Diabetic Gastroparesis Pankaj J. Pasricha, Ajitha Mannalithara, Alka Mithal, Amrita Sehgal, John M. Morton, Gurkirpal Singh Introduction and background: Gastroparesis is a disorder that encompasses a spectrum of symptoms associated with delayed gastric emptying in the absence of mechanical obstruction. The two most common forms of gastroparesis are diabetic and idiopathic, together comprising 90% or more of cases. Clinical experience suggests that both forms of the syndrome are probably heterogeneous in nature, with subsets that differ in their response to treatment and long-term prognosis. The aim of this study was to study US hospitalizations to determine if non-diabetic and diabetic causes of gastroparesis differed with respect to demographics and healthcare burden. Methods: The Nationwide Inpatient Sample (NIS) is a stratified random sample of all US community hospitals. It is the largest inpatient care database in the US and the only database that has information on all inpatient care regardless of insurance status. NIS's large sample size and data sampling techniques allow calculation of national estimates for particular diagnoses and analysis of secular trends. Using the NIS database, we analyzed the frequency, mortality, age, gender, ethnicity, length of stay, and cost of hospitalization in all inpatient hospitalizations with a primary diagnosis of gastroparesis between 1994 - 2005. Diabetic and non-diabetic gastroparesis were identified based on the presence or absence of secondary diagnosis codes of diabetes. All results are reported as means +/- standard error. Results: During 12 years of observation, the number of hospitaliza- tions with a primary diagnosis of non-diabetic gastroparesis (NDGP) were nearly 3-fold greater than those with a primary diagnosis of diabetic gastroparesis (DGP)( 54,161 and 18,400 for DGP and NDGP respectively). As compared with DGP, NDGP patients were younger (50.71+/- 0.19 years vs 54.98+/- 0.27 years; p = <0.0001) and more likely to be females (72.91% vs 65.32%; p = <0.0001). Further, NDGP patients were mostly white (58.8%) compared to DGP patients (41.4% white, p = <0.0001). NDGP patients had a higher length of hospitalization as compared with DGP (6.53+/- 0.08 vs 5.17+/- 0.09; p = <0.0001), and this was associated with a higher cost ($18,214+/- 281.26 vs $14,769+/- 396.32; P = <0.0001). All cause mortality was higher by a factor of nearly 1.3 (0.87% vs 0.72%; p = 0.47), Conclusions: Non-diabetic gastroparesis is a significant healthcare problem in this country and has distinct demographic and ethnic characteristics as compared with diabetic gastroparesis. Our results should form the basis for further clinical and pathophysiol- ogical studies to understand the biological basis for gastroparesis in the non-diabetic popula- tion. T1353 Magnetic Resonance Imaging of Dynamic Volume Change After a Meal: Inter- Observer Variability and Data Analysis Heiko Fruehauf, Dieter Menne, Zsofia Forras-Kaufman, Elad Kaufman, Monika A. Kwiatek, Michael Fried, Werner Schwizer, Mark R. Fox INTRODUCTION: Magnetic resonance (MR) imaging provides direct, non-invasive measure- ments of gastric function and emptying. The inter-observer variability (IOV) of MR volume measurements and the appropriate analysis of MR data have not been established. AIM: To assess (1) IOV of total gastric volume (TGV) and gastric contents volume (GCV) measurements from MR images. (2) Frequency of MR scans needed to describe dynamic volume change after a meal. (3) Ability of standard power exponential (PowExp) model of Elashof, and a novel linear exponential (LinExp) model to describe MR data. METHOD: 10 healthy volun- teers received three different volumes of a liquid nutrient test meal (200-800ml) on three days in randomized order. MRI was performed in supine position by a 1.5T system every 1 min for the first 10 min of gastric emptying, every 2 min from 10-20 min and then every 5 min up to 90 min. Measurements of TGV and GCV were analyzed independently by three observers. Volume data was fitted by the PowExp and LinExp models in a single population fit to stabilize parameter estimates of gastric volume change and gastric emptying half time (T50). RESULTS: An initial rise in GCV and TGV was often observed after meal ingestion (more prominent at smaller test meal volumes; ANOVA p<0.001) indicating that gastric secretion can be greater than emptying in the initial postprandial period [Goetze et al. DDW07]. Thereafter GCV and TGV decreased in an approximately linear fashion. (1) IOV decreased exponentially as GCV or TGV increased (ANOVA p<0.001) from 12% at 200ml to 8% at 400ml to 6% at 600 and 800ml. IOV for T50 was <5%. (2) By dropping data at random time points and refitting the models, it was determined that an accurate description of postprandial volume change demanded measurements every 2 min for a 10-20 min period (shorter after larger test meals) after which less frequent measurements were required. (3) Both models provided comparable estimates of T50; however the PowExp model did not describe the dynamic change observed in the early postprandial period. In contrast any initial volume rise was parameterized by the LinExp model allowing the effect of this phenonema on gastric emptying T50 to be assessed. CONCLUSION: Gastric MR provides quantitative measurements of volume change after a meal with low IOV unless the stomach is nearly empty. Frequent measurements are required in the initial postprandial period when a volume rise is frequently seen before GCV and TGV start to fall. The novel LinExp model describes the postprandial volume changes observed by MR imaging more accurately than the PowExp model used in conventional gastric emptying tests. T1354 Utility of Antroduodenal Manometry Prior to Gastric Electrical Stimulation Jesse Liu, Linda Anh B. Nguyen, Amy J. Marincek, Shelly Parker, William J. Snape Purpose: It is unknown whether manometric patterns identified by antroduodenal manometry (ADM) correlate with response to gastric electrical stimulation (GES). The aims of our study are 1) to categorize and determine the prevalence of manometric abnormalities in patients with medically refractory gastroparesis requiring GES and 2) to identify ADM patterns which predict clinical improvement after GES. Methods: 31 patients who underwent Enterra GES (Medtronic, Inc) for medically refractory gastroparesis were analyzed [mean follow up 19 AGA Abstracts