Small intestinal glucose absorption and duodenal motility in type 1 diabetes mellitus

Vitamin E (α-Tocopherol) Does Not Ameliorate the Toxic Effect of Bisphenol S on the Metabolic Analytes and Pancreas Histoarchitecture of Diabetic Rats

This study investigated whether the coadministration of vitamin E (VitE) diminishes the harmful effects provoked by plasticizer bisphenol S (BPS) in the serum metabolites related to hepatic and renal metabolism, as well as the endocrine pancreatic function in diabetic male Wistar rats. Rats were divided into five groups (n = 5-6); the first group was healthy rats (Ctrl group). The other four groups were diabetic rats induced with 45 mg/kg bw of streptozotocin: Ctrl-D (diabetic control); VitE-D (100 mg/kg bw/d of VitE); BPS-D (100 mg/kg bw/d of BPS); The animals from the VitE + BPS-D group were administered 100 mg/kg bw/d of VitE + 100 mg/kg bw/d of BPS. All compounds were administered orally for 30 days. Body weight, biochemical assays, urinalysis, glucose tolerance test, pancreas histopathology, proximate chemical analysis in feces, and the activity of antioxidants in rat serum were assessed. The coadministration of VitE + BPS produced weight losses, increases in 14 serum analytes, and degeneration in the pancreas. Therefore, the VitE + BPS coadministration did not have a protective effect versus the harmful impact of BPS or the diabetic metabolic state; on the contrary, it partially aggravated the damage produced by the BPS. VitE is likely to have an additive effect on the toxicity of BPS.

Hibiscus sabdariffa L. polyphenolic-rich extract promotes muscle glucose uptake and inhibits intestinal glucose absorption with concomitant amelioration of Fe2+ -induced hepatic oxidative injury

In this current study, the antidiabetic effectiveness of Hibiscus sabdariffa and its protective function against Fe²⁺ -induced oxidative hepatic injury were elucidated using in vitro, in silico, and ex vivo studies. The oxidative damage was induced in hepatic tissue by incubation with 0.1 mMolar ferrous sulfate (FeSO4) and then treated with different concentrations of crude extracts (ethyl acetate, ethanol, and aqueous) of H. sabdariffa flowers for 30 min at 37°C. When compared to ethyl acetate and aqueous extracts, the ethanolic extract displayed the most potent scavenging activity in ferric-reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and nitric oxide (NO) assays, with IC₅₀ values of 2.8 μl/ml, 3.3 μl/ml, and 9.2 μl/ml, respectively. The extracts significantly suppressed α-glucosidase and α-amylase activities (p < .05), with the ethanolic extract demonstrating the highest activity. H. sabdariffa significantly (p < .05) raised reduced glutathione (GSH) levels while simultaneously decreasing malondihaldehyde (MDA) and NO levels and increasing superoxide dismutase (SOD) and catalase activity in Fe²⁺ induced oxidative hepatic injury. The extract of the plant inhibited intestinal glucose absorption and increased muscular glucose uptake. The extract revealed the presence of several phenolic compounds when submitted to gas chromatography-mass Spectroscopy (GC-MS) screening, which was docked with α-glucosidase and α- amylase. The molecular docking displayed the compound 4-(3,5-Di-tert-butyl-4-hydroxyphenyl)butyl acrylate strongly interacted with α-glucosidase and α-amylase and had the lowest free binding energy compared to other compounds and acarbose. These results suggest that H. sabdariffa has promising antioxidant and antidiabetic activity. PRACTICAL APPLICATIONS: In recent years, there has been increased concern about the side effects of synthetic anti-diabetic drugs, as well as their expensive cost, especially in impoverished nations. This has instigated a radical shift towards the use of traditional plants, which are rich in phytochemicals many years ago. Among these plants, H. sabdariffa has been used to treat diabetes in traditional medicine. In this present study, H. sabdariffa extracts demonstrated the ability to inhibit carbohydrate digesting enzymes, facilitate muscle glucose uptake and attenuate oxidative stress in oxidative hepatic injury. Hence, demonstrating H. sabdariffa's potential to protect against oxidative damage and the complications associated with diabetes. Consumption of Hibiscus tea or juice may be a potential source for developing an anti-diabetic drug.

Gastrointestinal autonomic neuropathy in diabetes

Gastrointestinal autonomic neuropathy represents an important and diverse, but poorly appreciated, manifestation of diabetic autonomic neuropathy that impacts negatively on quality of life. There is no test to assess gastrointestinal autonomic nerve damage directly in humans; cardiovascular autonomic reflex tests are often used as a surrogate, but are suboptimal. Gastrointestinal symptoms are common in diabetes, but usually correlate only weakly with disordered motility. Diabetic gastroparesis, or abnormally delayed gastric emptying, occurs frequently and is the best characterized manifestation of gastrointestinal autonomic neuropathy. There is a bi-directional relationship between postprandial glycaemia and the rate of gastric emptying. However, autonomic neuropathy can affect the function of any gut segment from the esophagus to the anus. Current management options for gastrointestinal autonomic neuropathy are, for the main part, empirical and sub-optimal.

Effect of Diabetes Mellitus on the Pharmacokinetics and Pharmacodynamics of Tuberculosis Treatment

Diabetes mellitus (DM) and tuberculosis (TB) are two common diseases with increasing geographic overlap and clinical interactions. The effect of DM and hemoglobin A1c (HbA1c) values on the pharmacokinetics (PK) and pharmacodynamics (PD) of anti-TB drugs remains poorly characterized. Newly diagnosed TB patients with and without DM starting fixed-dose, thrice-weekly treatment underwent sampling for PK assessments (predose and 0.5, 2, and 6 h postdose) during the intensive and continuation phases of treatment. The effect of DM and HbA1c values on the maximum concentration (C _max) of rifampin, isoniazid, and pyrazinamide and the association between drug concentrations and microbiologic and clinical outcomes were assessed. Of 243 patients, 101 had DM. Univariate analysis showed significant reductions in the C _max of pyrazinamide and isoniazid (but not rifampin) with DM or increasing HbA1c values. After adjusting for age, sex, and weight, DM was associated only with reduced pyrazinamide concentrations (adjusted geometric mean ratio = 0.74, P = 0.03). In adjusted Cox models, female gender (adjusted hazards ratio [aHR] = 1.75, P = 0.001), a lower smear grade with the Xpert assay (aHR = 1.40, P < 0.001), and the pyrazinamide C _max (aHR = 0.99, P = 0.006) were independent predictors of sputum culture conversion to negative. Higher isoniazid or rifampin concentrations were associated with a faster time to culture conversion in patients with DM only. A pyrazinamide C _max above the therapeutic target was associated with higher unfavorable outcomes (treatment failure, relapse, death) (odds ratio = 1.92, P = 0.04). DM and higher HbA1c values increased the risk of not achieving therapeutic targets for pyrazinamide (but not rifampin or isoniazid). Higher pyrazinamide concentrations, though, were associated with worse microbiologic and clinical outcomes. DM status also appeared to influence PK-PD relationships for isoniazid and rifampin.

Disordered control of intestinal sweet taste receptor expression and glucose absorption in type 2 diabetes

We previously established that the intestinal sweet taste receptors (STRs), T1R2 and T1R3, were expressed in distinct epithelial cells in the human proximal intestine and that their transcript levels varied with glycemic status in patients with type 2 diabetes. Here we determined whether STR expression was 1) acutely regulated by changes in luminal and systemic glucose levels, 2) disordered in type 2 diabetes, and 3) linked to glucose absorption. Fourteen healthy subjects and 13 patients with type 2 diabetes were studied twice, at euglycemia (5.2 ± 0.2 mmol/L) or hyperglycemia (12.3 ± 0.2 mmol/L). Endoscopic biopsy specimens were collected from the duodenum at baseline and after a 30-min intraduodenal glucose infusion of 30 g/150 mL water plus 3 g 3-O-methylglucose (3-OMG). STR transcripts were quantified by RT-PCR, and plasma was assayed for 3-OMG concentration. Intestinal STR transcript levels at baseline were unaffected by acute variations in glycemia in healthy subjects and in type 2 diabetic patients. T1R2 transcript levels increased after luminal glucose infusion in both groups during euglycemia (+5.8 × 10(4) and +5.8 × 10(4) copies, respectively) but decreased in healthy subjects during hyperglycemia (-1.4 × 10(4) copies). T1R2 levels increased significantly in type 2 diabetic patients under the same conditions (+6.9 × 10(5) copies). Plasma 3-OMG concentrations were significantly higher in type 2 diabetic patients than in healthy control subjects during acute hyperglycemia. Intestinal T1R2 expression is reciprocally regulated by luminal glucose in health according to glycemic status but is disordered in type 2 diabetes during acute hyperglycemia. This defect may enhance glucose absorption in type 2 diabetic patients and exacerbate postprandial hyperglycemia.

Plasma insulin and glucose time courses after biliary pancreatic diversion in morbidly obese patients with and without diabetes

BACKGROUND

The exact mechanism for the dramatic effect of surgical procedures for obesity on type 2 diabetes remains unknown.

METHODS

Five diabetic morbidly obese patients and 5 nondiabetic morbidly obese patients undergoing biliopancreatic diversion were compared retrospectively. A 75-g trans-gastrostomy glucose tolerance test was administered on the fifth day postoperatively and a standard 75-g oral glucose tolerance test was performed on the seventh day postoperatively, with blood sampling for measuring plasma glucose and insulin levels at 0, 30, 60, 90, 120, and 180 minutes.

RESULTS

All 5 diabetic patients were shown, at the same time, still to have diabetes or an impaired glucose tolerance test when tested through the biliopancreatic limb but patients were normal when tested through the new alimentary channel. No significant difference was seen in the nondiabetic patients.

CONCLUSIONS

Biliopancreatic diversion can completely normalize the glycemic cycle in type 2 diabetes patients in the week after the intervention, even before any significant weight loss has occurred. The surgical procedure itself, designed to exclude most of the stomach, duodenum, and part of the jejunum, directly affects carbohydrate homeostasis.

Glucose absorption and small intestinal transit in critical illness

OBJECTIVES

Although enteral nutrition is standard care for critically ill patients, nutrient absorption has not been quantified in this group and may be impaired due to intestinal dysmotility. The objectives of this study were to measure small intestinal glucose absorption and duodenocecal transit and determine their relationship with glycemia in the critically ill.

DESIGN

Prospective observational study of healthy and critically ill subjects.

SETTING

Tertiary mixed medical-surgical adult intensive care unit.

SUBJECTS

Twenty-eight critically ill patients and 16 healthy subjects were studied. MATERIALS AND MAIN RESULTS: Liquid feed (100 kcal/100 mL), labeled with Tc-sulfur colloid and including 3 g of 3-O-methylglucose, was infused into the duodenum. Glucose absorption and duodenocecal transit were measured using the area under the 3-O-methylglucose concentration curve and scintigraphy, respectively. Data are median (range).

RESULTS AND DISCUSSION

Glucose absorption was reduced in critical illness when compared to health (area under the concentration curve: 16 [1-32] vs. 20 [14-34] mmol/L·min; p = .03). Small intestinal transit times were comparable in patients and healthy subjects (192 [9-240] vs. 168 [6-240] min; p = .99) and were not related to glucose absorption. Despite higher fasting blood glucose concentrations (6.3 [5.1-9.3] vs. 5.7 [4.6-7.6] mmol/L; p < .05), the increment in blood glucose was sustained for longer in the critically ill (Δ glucose at t = 60; 1.9 [-2.1-5.0] mmol/L vs. -0.2 [-1.3-2.3] mmol/L; p < .01).

CONCLUSIONS

Critical illness is associated with reduced small intestinal glucose absorption, but despite this, the glycemic response to enteral nutrient is sustained for longer.

Sensing via intestinal sweet taste pathways

The detection of nutrients in the gastrointestinal (GI) tract is of fundamental significance to the control of motility, glycemia and energy intake, and yet we barely know the most fundamental aspects of this process. This is in stark contrast to the mechanisms underlying the detection of lingual taste, which have been increasingly well characterized in recent years, and which provide an excellent starting point for characterizing nutrient detection in the intestine. This review focuses on the form and function of sweet taste transduction mechanisms identified in the intestinal tract; it does not focus on sensors for fatty acids or proteins. It examines the intestinal cell types equipped with sweet taste transduction molecules in animals and humans, their location, and potential signals that transduce the presence of nutrients to neural pathways involved in reflex control of GI motility.

Effects of metoclopramide on duodenal motility and flow events, glucose absorption, and incretin hormone release in response to intraduodenal glucose infusion

The contribution of small intestinal motor activity to nutrient absorption is poorly defined. A reduction in duodenal flow events after hyoscine butylbromide, despite no change in pressure waves, was associated with reduced secretion of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and a delay in glucose absorption. The aim of this study was to investigate the effect of metoclopramide on duodenal motility and flow events, incretin hormone secretion, and glucose absorption. Eight healthy volunteers (7 males and 1 female; age 29.8 ± 4.6 yr; body mass index 24.5 ± 0.9 kg/m²) were studied two times in randomized order. A combined manometry and impedance catheter was used to measure pressure waves and flow events in the same region of the duodenum simultaneously. Metoclopramide (10 mg) or control was administered intravenously as a bolus, followed by an intraduodenal glucose infusion for 60 min (3 kcal/min) incorporating the ¹⁴C-labeled glucose analog 3-O-methylglucose (3-OMG). We found that metoclopramide was associated with more duodenal pressure waves and propagated pressure sequences than control (P < 0.05 for both) during intraduodenal glucose infusion. However, the number of duodenal flow events, blood glucose concentration, and plasma 3-[¹⁴C]OMG activity did not differ between the two study days. Metoclopramide was associated with increased plasma concentrations of GLP-1 (P < 0.05) and GIP (P = 0.07) but lower plasma insulin concentrations (P < 0.05). We concluded that metoclopramide was associated with increased frequency of duodenal pressure waves but no change in duodenal flow events and glucose absorption. Furthermore, GLP-1 and GIP release increased with metoclopramide, but insulin release paradoxically decreased.

Effects of physiological hyperglycemia on duodenal motility and flow events, glucose absorption, and incretin secretion in healthy humans

CONTEXT

Acute hyperglycemia slows gastric emptying, but its effects on small intestinal motor activity and glucose absorption are unknown. In type 2 diabetes, the postprandial secretion of glucose-dependent insulinotropic polypeptide (GIP) is preserved, but that of glucagon-like peptide-1 (GLP-1) is possibly reduced; whether the latter is secondary to hyperglycemia or diabetes per se is unknown.

AIM

The aim was to investigate the effects of acute hyperglycemia on duodenal motility and flow events, glucose absorption, and incretin hormone secretion.

METHODS

Nine healthy volunteers were studied on two occasions. A combined manometry/impedance catheter was positioned in the duodenum. Blood glucose was clamped at either 9 mmol/liter (hyperglycemia) or 5 mmol/liter (euglycemia) throughout the study. Manometry and impedance recordings continued between T=-10 min and T=180 min. Between T=0 and 60 min, an intraduodenal glucose infusion was given (approximately 3 kcal/min), together with 14C-labeled 3-O-methylglucose (3-OMG) to evaluate glucose absorption.

RESULTS

Hyperglycemia had no effect on duodenal pressure waves or flow events during the 60 min of intraduodenal glucose infusion, when compared to euglycemia. During hyperglycemia, there was an increase in plasma GIP (P<0.05) and 14C-3-OMG (P<0.05) but no effect on GLP-1 concentrations in response to the intraduodenal infusion, compared to euglycemia.

CONCLUSION

Acute hyperglycemia in the physiological range has no effect on duodenal pressure waves and flow events but is associated with increased GIP secretion and rate of glucose absorption in response to intraduodenal glucose.

Insulin secretion in healthy subjects and patients with Type 2 diabetes--role of the gastrointestinal tract

Postprandial glycaemia is now recognised as the major determinant of average glycaemic control in type 2 diabetes, as assessed by glycated haemoglobin. Therefore, an understanding of the factors influencing both the rise in blood glucose and insulin secretion after a meal is fundamental to the development of dietary and pharmacological approaches to optimise glycaemic control. The gastrointestinal tract regulates the rate at which carbohydrate and other nutrients are absorbed and is the source of regulatory peptides that stimulate pancreatic insulin secretion in the setting of elevated blood glucose levels. This article highlights the importance of the gastrointestinal tract in insulin secretion and glucose homeostasis and discusses potential strategies directed at modification of gastrointestinal function in order to improve glycaemic control in the management of diabetes.

Effects of intraluminal local anesthetic on upper gastrointestinal motor, sensory, and peptide hormone responses to intraduodenal glucose

OBJECTIVE

Enterally administered glucose modifies gut sensation, diminishes hunger, and slows gastric emptying by suppressing antral motility and stimulating pyloric pressures. We aimed to clarify the mechanism of small intestinal glucose sensing.

METHODS

We studied eight healthy males twice, in random order. An antroduodenal manometry catheter was positioned with a sleeve sensor across the pylorus. Benzocaine, or vehicle alone, was given into the proximal duodenum as a bolus, followed by continuous infusion for 105 min (T=-15 to 90 min). Glucose was also infused into the proximal duodenum at 3 kcal/min for 90 min (T=0-90 min). Sensations of hunger, bloating, and nausea were assessed with visual analog questionnaires, blood was sampled at intervals, and energy intake at a buffet meal (T=90-120 min) was measured.

RESULTS

Perceptions of bloating and nausea were markedly less with benzocaine when compared with vehicle (P<0.05 for each), with no difference in hunger, or energy intake. In contrast, the suppression of antral waves and stimulation of phasic and tonic pyloric pressures, duodenal waves, and propagated duodenal wave sequences by intraduodenal glucose infusion did not differ between the 2 days. No difference in blood glucose, plasma insulin, or plasma glucagon-like peptide 1 between benzocaine and control was observed, whereas glucose-dependent insulinotropic polypeptide and cholecystokinin concentrations were slightly higher with benzocaine (P<0.05 for both).

CONCLUSION

Mucosal anesthesia ameliorates unpleasant sensations induced by enteral glucose, but does not inhibit the release of gut peptides that feed back on appetite and gastroduodenal motility.

Glucose absorption and gastric emptying in critical illness

INTRODUCTION

Delayed gastric emptying occurs frequently in critically ill patients and has the potential to adversely affect both the rate, and extent, of nutrient absorption. However, there is limited information about nutrient absorption in the critically ill, and the relationship between gastric emptying (GE) and absorption has hitherto not been evaluated. The aim of this study was to quantify glucose absorption and the relationships between GE, glucose absorption and glycaemia in critically ill patients.

METHODS

Studies were performed in nineteen mechanically-ventilated critically ill patients and compared to nineteen healthy subjects. Following 4 hours fasting, 100 ml of Ensure, 2 g 3-O-methyl glucose (3-OMG) and 99mTc sulphur colloid were infused into the stomach over 5 minutes. Glucose absorption (plasma 3-OMG), blood glucose levels and GE (scintigraphy) were measured over four hours. Data are mean +/- SEM. A P-value < 0.05 was considered significant.

RESULTS

Absorption of 3-OMG was markedly reduced in patients (AUC240: 26.2 +/- 18.4 vs. 66.6 +/- 16.8; P < 0.001; peak: 0.17 +/- 0.12 vs. 0.37 +/- 0.098 mMol/l; P < 0.001; time to peak; 151 +/- 84 vs. 89 +/- 33 minutes; P = 0.007); and both the baseline (8.0 +/- 2.1 vs. 5.6 +/- 0.23 mMol/l; P < 0.001) and peak (10.0 +/- 2.2 vs. 7.7 +/- 0.2 mMol/l; P < 0.001) blood glucose levels were higher in patients; compared to healthy subjects. In patients; 3-OMG absorption was directly related to GE (AUC240; r = -0.77 to -0.87; P < 0.001; peak concentrations; r = -0.75 to -0.81; P = 0.001; time to peak; r = 0.89-0.94; P < 0.001); but when GE was normal (percent retention240 < 10%; n = 9) absorption was still impaired. GE was inversely related to baseline blood glucose, such that elevated levels were associated with slower GE (ret 60, 180 and 240 minutes: r > 0.51; P < 0.05).

CONCLUSIONS

In critically ill patients; (i) the rate and extent of glucose absorption are markedly reduced; (ii) GE is a major determinant of the rate of absorption, but does not fully account for the extent of impaired absorption; (iii) blood glucose concentration could be one of a number of factors affecting GE.

The effects of insulin on glucose and fluid transport in the isolated small intestine of normal rats

Chronically administered insulin returns enhanced maximal glucose transport capacity induced by diabetes to its normal state. In this study, the direct and acute effects of insulin on glucose transport in different parts of isolated small intestine were investigated. Mucosal Fluid Transport (MFT), Mucosal Glucose Transport (MGT) and Serosal Glucose Transport (SGT) were measured in the presence and absence of insulin in averted sacs, prepared from female Wistar rats. This study shows that the presence of insulin in vitro (40 and 80 microU/mL) can reduce MGT and SGT in different segments of the small intestine (duodenum, jejunum and ileum) after 30 min whereas it had no effect on MFT. Mucosal glucose transfer rates in the duodenum, jejunum and ileum of the controls were 6.07+/-0.4, 6.34+/-0.62 and 6.43+/-0.47 mg/g tissue respectively which were significantly reduced to 3.82+/-0.93, 3.60+/-0.50 and 1.17+/-0.45 in the presence of 80 microU/mL of insulin. Serosal glucose transfer too was decreased significantly from 0.3+/-0.05, 0.57+/-0.07 and 0.43+/-.07 in the duodenum, jejunum and ileum to 0.16+/-0.03, 0.16+/-0.04 and .07+/-.02 respectively. Mucosal fluid transfer was not affected by insulin. Insulin was as effective whether it was added on the mucosal or the serosal side. The results of this study show that insulin can directly affect glucose transport in the small intestine; its physiological role must be examined. Direct effect of insulin deficiency on glucose absorption in diabetic patients may play a role in the pathophysiology of the disease.

Concurrent duodenal manometric and impedance recording to evaluate the effects of hyoscine on motility and flow events, glucose absorption, and incretin release

Upper gastrointestinal motor function and incretin hormone secretion are major determinants of postprandial glycemia and insulinemia. However, the impact of small intestinal flow events on glucose absorption and incretin release is poorly defined. Intraluminal impedance monitoring is a novel technique that allows flow events to be quantified. Eight healthy volunteers were studied twice, in random order. A catheter incorporating six pairs of electrodes at 3-cm intervals, and six corresponding manometry sideholes, was positioned in the duodenum. Hyoscine butylbromide (20 mg) or saline was given as an intravenous bolus, followed by a continuous intravenous infusion of either hyoscine (20 mg/h) or saline over 60 min. Concurrently, glucose and 3-O-methylglucose (3-OMG) were infused into the proximal duodenum (3 kcal/min), with frequent blood sampling to measure glucose, 3-OMG, insulin, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). The frequency of duodenal pressure waves and propagated pressure wave sequences was reduced by hyoscine in the first 10 min (P<0.01 for both), but not after that time. In contrast, there were markedly fewer duodenal flow events throughout 60 min with hyoscine (P<0.005). Overall, blood glucose (P<0.01) and plasma 3-OMG concentrations (P<0.05) were lower during hyoscine than saline, whereas plasma insulin, GLP-1, and GIP concentrations were initially (t=20 min) lower during hyoscine (P<0.05). In conclusion, intraluminal impedance measurement may be more sensitive than manometry in demonstrating alterations in duodenal motor function. A reduction in the frequency of duodenal flow events is associated with a decreased rate of glucose absorption and incretin release in healthy subjects.

Upper gastrointestinal function and glycemic control in diabetes mellitus

Recent evidence has highlighted the impact of glycemic control on the incidence and progression of diabetic micro- and macrovascular complications, and on cardiovascular risk in the non-diabetic population. Postprandial blood glucose concentrations make a major contribution to overall glycemic control, and are determined in part by upper gastrointestinal function. Conversely, poor glycemic control has an acute, reversible effect on gastrointestinal motility. Insights into the mechanisms by which the gut contributes to glycemia have given rise to a number of novel dietary and pharmacological strategies designed to lower postprandial blood glucose concentrations.

Stimulation of small intestinal burst activity in the postprandial state differentially affects lipid and glucose absorption in healthy adult humans

Small intestinal motor activity is important for the optimal digestion and absorption of nutrients. These motor responses to feeding are frequently abnormal during critical illness, with the persistence of migrating bursts of contractions during enteral feeding. Whether this disturbance influences nutrient absorption is not known. In this study, the effects of small intestinal burst activity on lipid and glucose absorption were evaluated in 10 healthy human adults (6 males, 4 females, 19-47 yr). Upper gastrointestinal manometry was recorded for 6 h during and shortly after a 20-min intravenous infusion of either erythromycin (1 mg/kg), to stimulate burst activity, or saline (0.9%) in a double-blind randomized fashion. Simultaneously with the start of the intravenous infusion, 60 ml liquid feed mixed with 200 microl 13C-triolein and 2 g 3-O-methylglucose (3-OMG) was infused intraduodenally for 30 min. Absorption of lipid and glucose was assessed using the [13C]triolein breath test and plasma concentrations of 3-OMG, respectively. Infusion of erythromycin was followed by a more rapid onset of burst activity following commencement of the duodenal infusion compared with saline (30 +/- 6.1 vs. 58 +/- 10.7 min; P < 0.05). Erythromycin was associated with a slower recovery of 13CO2 (P < 0.01). A positive correlation existed between the time to onset of burst activity and 13CO2 recovery (P < 0.001). Erythromycin had no effect on 3-OMG absorption. In conclusion, stimulation of small intestinal burst activity reduces the rate of lipid absorption but not glucose absorption in healthy human adults.

Small intestinal motility

PURPOSE OF REVIEW

In the past year, many studies were published in which new and relevant information on small intestinal motility in humans and laboratory animals was obtained.

RECENT FINDINGS

Although the reported findings are heterogeneous, some themes appear to be particularly interesting and novel. Among these is the association between disordered small intestinal motility and bacterial overgrowth of the small intestine. Studies in patients with portal hypertension, in patients with chronic renal failure, and in a rat model of experimental acute pancreatitis all point in the same direction. Another topic of particular interest is the relation between duodenal motility and glucose absorption; propagated duodenal pressure wave sequences are positively related to glucose absorption. Finally, many studies addressed the mechanisms involved in the regulation of interdigestive and postprandial small intestinal motility. These confirmed the key role of cholecystokinin and provided new information on the role of orexin A and leptin.

SUMMARY

The new information on intestinal motility gathered in the past year provides a greater insight in the pathophysiology of a number of diseases and will stimulate further studies in laboratory animals and in human subjects.