Plasma Glucose Kinetics Research Articles

The addition of mycoprotein to a mixed-meal impacts postprandial glucose kinetics without altering blood glucose concentrations: a randomised controlled trial

BackgroundMycoprotein is a high-fibre food previously shown to reduce postprandial glucose concentrations when ingested within a mixed-meal. We applied a dual stable isotope tracer approach to determine whether this is due to a reduced rate of appearance of glucose, in participants of ranging BMI.MethodsTwenty-four adults (F = 8, BMI 30 ± 6 kg·m−2) attended 2 trials in a double-blind, randomised, cross-over design. Participants ingested two energy and macronutrient matched milk-based drinks (enriched with 1000 mg [U-13C6] glucose in a subset of 12 participants), containing 50 g glucose and either 0 (CON) or 20 g (MYC) mycoprotein. A primed continuous intravenous infusion of D-[6,6-2H2] glucose determined plasma glucose kinetics over 6 h. Postprandial time-course, and AUC, of glucose and insulin concentration, rate of disappearance (RdT) and appearance of exogenous (RaEx), endogenous (EGP), and total (RaT) plasma glucose were assessed using two- and one-way ANOVA.ResultsDrink ingestion increased blood glucose and serum insulin concentrations (P < 0.05) and were comparable between conditions (P > 0.05). Both RaT and RdT were higher with MYC compared with CON over 6 h (mean 6 h glucose appearance and disappearance increased by 5 and 9%, respectively, P < 0.05). RaEx was not affected by MYC ingestion over 6 h (P > 0.05). The mean contribution of EGP to total glucose appearance was 15% greater with MYC, with a trend towards significance (P = 0.05). There was no relationship between BMI and the response to MYC ingestion for any of the variables (P < 0.05).ConclusionThe ingestion of mycoprotein within a mixed-meal impacted postprandial glucose kinetics, but not blood glucose or serum insulin concentrations, in individuals of ranging BMI.Clinical trial registry number and websiteThis trial was registered at clinicaltrials.gov as NCT04084639 and can be accessed at https://clinicaltrials.gov/ct2/show/NCT04084639.

Metformin and exercise effects on postprandial insulin sensitivity and glucose kinetics in pre-and-diabetic adults.

The potential interaction between metformin and exercise on glucose-lowering effects remains controversial. We studied the separated and combined effects of metformin and/or exercise on fasting and postprandial insulin sensitivity in individuals with pre- and - type 2 diabetes (T2D). Eight T2D adults (60±4 years) with overweight/obesity (32±4 kg·m-2) under chronic metformin treatment (9±6 years; 1281±524 mg·day-1) underwent four trials; a) taking their habitual metformin treatment (MET), b) substituting during 96 h their metformin medication by placebo (PLAC), c) placebo combined with 50 min bout of high-intensity interval exercise (PLAC+EX), and d) metformin combined with exercise (MET+EX). Plasma glucose kinetics using stable isotopes (6,6-2H2 and [U-13C] glucose), and glucose oxidation by indirect calorimetry, were assessed at rest, during exercise, and in a subsequent oral glucose tolerance test (i.e., OGTT). Postprandial glucose and insulin concentrations were analyzed as mean and incremental area under the curve (iAUC), and insulin sensitivity was calculated (i.e., MATSUDAindex and OGISindex). During OGTT, metformin reduced glucose iAUC (i.e., MET and MET+EX lower than PLAC and PLAC+EX, respectively; P=0.023). MET+EX increased MATSUDAindex above PLAC (4.8±1.4 vs 3.3±1.0, respectively; P=0.018) and OGISindex above PLAC (358±52 vs 306±46 mL·min-1·m-2, respectively; P=0.006). Metformin decreased plasma appearance of the ingested glucose (Ra OGTT; MET vs PLAC, -3.5; 95% CI -0.1 to -6.8 µmol·kg-1·min-1; P=0.043). Metformin combined with exercise potentiates insulin sensitivity during an OGTT in individuals with pre- and - type 2 diabetes. Metformin's blood glucose-lowering effect seems mediated by decreased oral glucose entering the circulation (gut-liver effect) an effect partially blunted after exercise.

Acute Statin Withdrawal Does not Interfere With the Improvements of a Session of Exercise in Postprandial Metabolism.

The risk for atherogenic plaque formation is high after ingestion of meals in individuals with high blood lipid levels (ie, dyslipidemia). Statins and exercise reduce the rise of blood triglyceride concentrations after a meal, but the effect of their combination is unclear. In a randomized crossover design, 11 individuals with dyslipidemia and metabolic syndrome treated with statins underwent a mixed-meal (970 ± 111 kcal, 24% fat, and 34% carbohydrate) tolerance test. Plasma lipid concentrations, fat oxidation, glucose, and glycerol kinetics were monitored immediately prior and during the meal test. Trials were conducted with participants under their habitual statin treatment and 96 hours after blinded statin withdrawal. Trials were duplicated after a prolonged bout of low-intensity exercise (75 minutes at 53 ± 4% maximal oxygen consumption) to study the interactions between exercise and statins. Statins reduced postprandial plasma triglycerides from 3.03 ± 0.85 to 2.52 ± 0.86 mmol·L-1 (17%; P = .015) and plasma glycerol concentrations (ie, surrogate of whole-body lipolysis) without reducing plasma free fatty acid concentration or fat oxidation. Prior exercise increased postprandial plasma glycerol levels (P = .029) and fat oxidation rates (P = .024). Exercise decreased postprandial plasma insulin levels (241 ± 116 vs 301 ± 172 ρmol·L-1; P = .026) but not enough to increase insulin sensitivity (P = .614). Neither statins nor exercise affected plasma glucose appearance rates from exogenous or endogenous sources. In dyslipidemic individuals, statins reduce blood triglyceride concentrations after a meal, but without limiting fat oxidation. Statins do not interfere with exercise lowering the postprandial insulin that likely promotes fat oxidation. Last, statins do not restrict the rates of plasma incorporation or oxidation of the ingested glucose.

EFFECTS OF STATINS ON SUBSTRATE UTILIZATION DURING EXERCISE

PURPOSE: Statin is the most prescribed medicine worldwide to lower cardiovascular risk. Its blood triglyceride lowering effect, may limit fat mobilization/oxidation during exercise. METHODS: Nine individuals with metabolic syndrome, chronically treated with statins to correct their dyslipidemia exercised at three increasing intensities (40, 70, and 85% VO2 MAX) while taking statins or placebo using a randomized double-blind crossover design. Indirect calorimetry and stable isotope tracer techniques were combined to assess plasma substrate kinetic and oxidation. RESULTS: As expected, statin use lowered resting plasma triglyceride concentration (i.e., PLAC 1.4±0.7 vs STAT 1.1±0.5 mmol·L-1, p = 0.003), and also plasma triglyceride concentration during exercise (i.e., PLAC 1.7±0.8 vs STAT 1.2±0.5 mmol·L-1; p < 0.001). Ra glycerol (i.e., index of whole-body lipolysis) increased along with exercise intensity but the increase was attenuated by statins (p < 0.014) at the 85% VO2 MAX exercise intensity (i.e., PLAC 7.4±1.9 vs STAT 5.8±2.2 mM·kg·min-1; p = 0.046). This 21% lower lipolysis during STAT did not limit fat oxidation that was similarly low in PLAC and STAT (i.e., PLAC 0.7±2.1 vs STAT 0.8±2.2 mM·kg·min-1; p = 0.459). STAT increased resting plasma glucose concentration (i.e., PLAC 6.6±1.6 vs STAT 6.8±1.6 mmol·L-1, p = 0.036) but did not affect exercise glucose or insulin plasma. Rates of glucose appearance (i.e., Ra glucose, index of liver glucose output) were similar during PLAC and STAT at rest and during exercise. Glucose disappearance rates increased during the first two exercise intensities (i.e., 40 and 70% VO2 MAX), but decreased in both groups at 85% VO2 explaining the ensuing hyperglycaemia at this intensity. CONCLUSIONS: Statin reduces exercise lipolysis during high intensity exercise, without affecting the already low rates of fat oxidation at that intensity. However, statin use does not affect plasma glucose kinetics or carbohydrate oxidation during exercise in a wide range of intensities in individuals chronically medicated with this drug.

O5. Effects of dietary fibre sources for sows during gestation on the performance and plasma glucose kinetics

O5. Effects of dietary fibre sources for sows during gestation on the performance and plasma glucose kinetics

Short communication: Effect of glucose infusion dose and stage of lactation on glucose tolerance test kinetics in lactating dairy cows

The objective for this study was to determine the effect of glucose dose and days following peak milk yield on plasma glucose, serum insulin, and plasma nonesterified fatty acids (NEFA) kinetics during an intravenous glucose tolerance test (IVGTT) in lactating dairy cattle. Six lactating Holstein dairy cows (3 primiparous and 3 multiparous) were assigned to 2 squares and received 0.092, 0.15, or 0.3 g of glucose/kg of body weight (BW) during an IVGTT at 74 and 221 d in milk (DIM), representing early (post-peak) lactation and mid lactation, respectively. Treatments were applied in a replicated Latin square design using contiguous 7-d periods within each stage of lactation. Milk production and dry matter intake were determined daily during the first 6 d of each period. The IVGTT was performed on d 7. For the IVGTT, cows were prepared with indwelling catheters in each jugular vein, and blood samples were collected at -15, -10, 5, 10, 15, 20, 30, 45, 60, 90, and 120 min relative to the glucose infusion. Samples were analyzed for plasma glucose, serum insulin, and plasma NEFA concentrations. Increasing the glucose dose during the IVGTT increased plasma glucose area under the curve (AUC), decreased glucose half-life, and increased maximal plasma glucose concentrations in plasma during the IVGTT. Greater glucose dose during the IVGTT elevated serum insulin AUC and increased nadir NEFA concentrations. Maximal plasma glucose concentration during the IVGTT was lower, whereas maximum NEFA concentration, NEFA AUC, and NEFA clearance rate were greater at 74 than at 221 DIM. Only glucose half-life was responsive to stage of lactation × glucose dose effects during the IVGTT, and the decrease in glucose half-life with increasing glucose dose was greater at 74 than at 221 DIM. Glucose AUC was greater and NEFA AUC lower for cows at 74 than at 221 DIM. For the doses tested, a glucose dose greater than 0.092 g/kg of BW resulted in peak blood glucose concentration that exceeded the previously reported renal glucose excretion threshold of 8.3 mM. There is a need for accompanying data to determine if this is the case for the glucose doses evaluated in this experiment. Based on maximal peak glucose concentrations and effects on glucose half-life, we identify 0.092 g of glucose/kg of BW (0.46 g/kg of metabolic body weight) as the preferred dose for the IVGTT for cows at 74 and 221 DIM in this study.

Lipid Intake Enhances Muscle Growth But Does Not Influence Glucose Kinetics in 3-Week-Old Low-Birth-Weight Neonatal Pigs

Low-birth-weight (LBWT) neonates grow at a slower rate than their normal-birth-weight (NBWT) counterparts and may develop hypoglycemia postnatally. We investigated whether dietary lipid supplementation would enhance growth and improve glucose production in LBWT neonatal pigs. Twelve 3-d-old NBWT (1.606 kg) crossbred pigs were matched to 12 LBWT (1.260 kg) same-sex littermates. At 6 d of age, 6 pigs in each group were fed a low-energy (LE) or a high-energy (HE) isonitrogenous formula containing 5.2% and 7.3% fat, respectively. Body composition was assessed using dual-energy X-ray absorptiometry; plasma glucose and glycerol kinetics were assessed using stable isotope tracers. After killing, weights of skeletal muscles and visceral organs were measured. Data were analyzed by ANOVA for a 2×2 factorial design; temporal effects were investigated using repeated-measures analysis. Lipid supplementation did not affect body weight of LBWT or NBWT pigs. However, liver and longissimus dorsi weights as a percentage of body weight were greater for pigs fed an HE diet than for those fed an LE diet (4.3% compared with 3.4% and 1.5% compared with 1.2%, respectively) but remained less for LBWT than for NBWT pigs (3.8% compared with 3.9% and 1.3% compared with 1.5%, respectively) (P<0.05). In addition, hepatic fat content increased (7.9 compared with 2.6 g) in pigs fed the HE compared with those fed the LE formula (P<0.05). Lipid supplementation did not influence plasma glucose concentration which remained lower in the LBWT than in the NBWT group (4.1 compared with 4.5 mmol/L) (P<0.05). Our data suggest that lipid supplementation modestly improved growth of skeletal muscle and the liver but did not affect glucose homeostasis in all groups, and glucose concentration remained lower in LBWT than in NBWT pigs. These data suggest that the previously reported hyperglycemic effect of lipid supplementation may depend on the route of administration or age of the neonatal pig.

Dataset for 'Pre-Exercise Breakfast Ingestion versus Extended Overnight Fasting Increases Postprandial Glucose Flux after Exercise in Healthy Men: Pre-exercise feeding and postprandial glucose flux'

The aim of this study was to characterise postprandial glucose flux after exercise in the fed versus overnight fasted-state and to investigate potential underlying mechanisms. In a randomized order, twelve men underwent breakfast-rest (BR; 3 h semi-recumbent), breakfast-exercise (BE; 2 h semi-recumbent before 60-min of cycling (50% peak power output) and overnight fasted-exercise (FE; as per BE omitting breakfast) trials. An oral glucose tolerance test (OGTT) was completed post-exercise (post-rest on BR). Dual stable isotope tracers ([U-13C] glucose ingestion and [6,6-2H2] glucose infusion) and muscle biopsies were combined to assess postprandial plasma glucose kinetics and intramuscular signaling, respectively. Plasma intestinal fatty acid binding (I-FABP) concentrations were determined as a marker of intestinal damage. The results from this study showed that consuming breakfast before exercise increases post-exercise postprandial plasma glucose disposal, which is offset (primarily) by increased appearance rates of orally-ingested glucose. Therefore, metabolic responses to fed-state exercise cannot be readily inferred from studies conducted in a fasted state.

Effect of alcohol ingestion on plasma glucose kinetics after Roux-en-Y gastric bypass surgery

BackgroundRoux-en-Y gastric bypass surgery (RYGB) increases the rate of alcohol absorption so that peak blood alcohol concentration is 2-fold higher after surgery compared with concentrations reached after consuming the same amount presurgery. Because high doses of alcohol can lead to hypoglycemia, patients may be at increased risk of developing hypoglycemia after alcohol ingestion. ObjectivesWe conducted 2 studies to test the hypothesis that the consumption of approximately 2 standard drinks of alcohol would decrease glycemia more after RYGB than before surgery. SettingSingle-center prospective randomized trial. MethodsWe evaluated plasma glucose concentrations and glucose kinetics (assessed by infusing a stable isotopically labelled glucose tracer) after ingestion of a nonalcoholic drink (placebo) or an alcoholic drink in the following groups: (1) 5 women before RYGB (body mass index = 43 ± 5 kg/m2) and 10 ± 2 months after RYGB (body mass index = 31 ± 7 kg/m2; study 1), and (2) 8 women who had undergone RYGB surgery 2.2 ± 1.2 years earlier (body mass index = 30 ± 5 kg/m2; study 2) ResultsCompared with the placebo drink, alcohol ingestion decreased plasma glucose both before and after surgery, but the reduction was greater before (glucose nadir placebo = −.4 ± 1.0 mg/dL versus alcohol = −9.6 ± 1.5 mg/dL) than after (glucose nadir placebo = −1.0 ± 1.6 mg/dL versus alcohol = −5.5 ± 2.6 mg/dL; P < .001) surgery. This difference was primarily due to an alcohol-induced early increase followed by a subsequent decrease in the rate of glucose appearance into systemic circulation. ConclusionRYGB does not increase the risk of hypoglycemia after consumption of a moderate dose of alcohol.

Preexercise breakfast ingestion versus extended overnight fasting increases postprandial glucose flux after exercise in healthy men.

The aim of this study was to characterize postprandial glucose flux after exercise in the fed versus overnight fasted state and to investigate the potential underlying mechanisms. In a randomized order, twelve men underwent breakfast-rest [(BR) 3 h semirecumbent], breakfast-exercise [(BE) 2 h semirecumbent before 60 min of cycling (50% peak power output)], and overnight fasted exercise [(FE) as per BE omitting breakfast] trials. An oral glucose tolerance test (OGTT) was completed after exercise (after rest on BR). Dual stable isotope tracers ([U-13C] glucose ingestion and [6,6-2H2] glucose infusion) and muscle biopsies were combined to assess postprandial plasma glucose kinetics and intramuscular signaling, respectively. Plasma intestinal fatty acid binding (I-FABP) concentrations were determined as a marker of intestinal damage. Breakfast before exercise increased postexercise plasma glucose disposal rates during the OGTT, from 44 g/120 min in FE {35 to 53 g/120 min [mean (normalized 95% confidence interval)] to 73 g/120 min in BE [55 to 90 g/120 min; P = 0.01]}. This higher plasma glucose disposal rate was, however, offset by increased plasma glucose appearance rates (principally OGTT-derived), resulting in a glycemic response that did not differ between BE and FE ( P = 0.11). Plasma I-FABP concentrations during exercise were 264 pg/ml (196 to 332 pg/ml) lower in BE versus FE ( P = 0.01). Breakfast before exercise increases postexercise postprandial plasma glucose disposal, which is offset (primarily) by increased appearance rates of orally ingested glucose. Therefore, metabolic responses to fed-state exercise cannot be readily inferred from studies conducted in a fasted state.

Effect of grinding process of steam-rolled barley grain on plasma glucose and leucine kinetics and protein synthesis in sheep

ABSTRACTAn isotope dilution method of [U-13C]glucose and [l-13C]leucine was simultaneously conducted to determine the effect of grinding process of steam-rolled barley grain on rates of plasma glucose and leucine turnover and whole-body protein synthesis (WBPS) in sheep. Six adult sheep were assigned to two dietary treatments and the experiment utilized a crossover design for two 21-day periods. The experimental diet was consisted of mixed hay and steam-rolled barley grain (1:1 ratio). Barley grain was treated either with or without grinding (GR diet and SR diet, respectively). Sheep were fed isoenergetically and isonitrogenously in both the treatments. The primed-continuous infusion method of [U-13C]glucose and [1-13C]leucine was simultaneously performed on day 21. The pH and ammonia concentrations in rumen fluid decreased (P < 0.05) and concentrations of total VFA, acetate, propionate and n-butyrate increased (P < 0.05) after feeding. Rates of plasma glucose and leucine turnover and WBPS did not differ between the dietary treatments. It is likely that grinding process of steam-rolled barley grain did not influence plasma glucose and leucine kinetics and WBPS in sheep fed the diets of mixed hay and barley grain at 1:1 ratio.

Effects of Chinese herbal medicine and cold exposure on plasma glucose, leucine and energy metabolism in sheep

An experiment was carried out to assess the feeding effect of Chinese herbal medicine on N balance, ruminal fermentation characteristics, kinetics of plasma glucose, leucine and energy metabolism in sheep kept at thermoneutral environment (23°C) or exposed to cold (2-4°C). Four sheep were subjected to either mixed hay (MH-diet) or hay supplemented with 2% of a traditional nourishing Chinese herbal medicine mixture (Astragalus root, Angelica root and Atractylodes rhizome; CHM-diet) over two 23-day periods using a crossover design. Cold exposure was conducted for 5days. The isotope dilution of [U-13 C]glucose with open circuit calorimetry was used to determine the turnover and oxidation rates of plasma glucose and metabolic heat production. The rate of plasma leucine turnover was measured with an isotope dilution method using [1-13 C]leucine. N intake was higher, N excretion through faeces was lower and N digestibility was higher for the CHM-diet than the MH-diet. Rumen pH was lower, concentration of rumen NH3 was higher, concentrations of rumen total VFA and acetate tended to be higher and propionate was higher for the CHM-diet compared with the MH-diet. Turnover rate of plasma glucose was higher for the CHM-diet than the MH-diet and increased during cold exposure. Oxidation rate of plasma glucose did not differ between diets and also between environments. Turnover rate of plasma leucine was higher for the CHM-diet compared with the MH-diet but remained similar between environments. Heat production was greater for the CHM-diet than the MH-diet and increased during cold exposure. No significant diet×environment interaction was detected. The present results demonstrated that plasma glucose and energy metabolism were enhanced by both Chinese herbal medicine and cold exposure; plasma leucine metabolism was enhanced by Chinese herbal medicine but with lack of change in response to cold exposure in sheep under the conditions of the current experiment.

Effect of feeding garlic leaves on rumen fermentation, methane emission, plasma glucose kinetics, and nitrogen utilization in sheep

BackgroundGarlic and its constituents are reported to have been effective in reducing methane emission and also influence glucose metabolism in body; however, studies in ruminants using garlic leaves are scarce. Garlic leaves contain similar compounds as garlic bulbs, but are discarded in field after garlic bulb harvest. We speculate that feeding garlic leaves might show similar effect as garlic constituents in sheep and could be potential animal feed supplement. Thus, we examined the effect of freeze dried garlic leaves (FDGL) on rumen fermentation, methane emission, plasma glucose kinetics and nitrogen utilization in sheep.MethodsSix sheep were fed Control diet (mixed hay and concentrate (60:40)) or FDGL diet (Control diet supplemented with FDGL at 2.5 g/kg BW0.75 of sheep) using a crossover design. Methane gas emission was measured using open-circuit respiratory chamber. Plasma glucose turnover rate was measured using isotope dilution technique of [U-13C]glucose. Rumen fluid, feces and urine were collected to measure rumen fermentation characteristics and nitrogen utilization.ResultNo significant difference in rumen fermentation parameters was noticed except for rumen ammonia tended to be higher (0.05 < P < 0.1) in FDGL diet. Methane emission per kg dry matter ingested and methane emission per kg dry matter digested were lower (P < 0.05) in FDGL diet. Plasma glucose concentration was similar between diets and plasma glucose turnover rate tended to be higher in FDGL diet (0.05 < P < 0.1). Nitrogen retention was higher (P < 0.05) and microbial nitrogen supply tended to be higher (0.05 < P < 0.1) in FDGL diet.ConclusionFDGL diet did not impair rumen fermentation, improved nitrogen retention; while absence of significant results in reduction of methane emission, glucose turnover rate and microbial nitrogen supply, further studies at higher dose would be necessary to conclude the merit of FDGL as supplement in ruminant feedstuff.

Recovery of insulin sensitivity and optimal body composition after rapid weight loss in obese dogs fed a high-protein medium-carbohydrate diet.

This study investigated the effects of an experimental high-protein medium-carbohydrate diet (protein level, 46% metabolizable energy, ME). First, postprandial plasma glucose and insulin kinetics were determined in steady-state overweight/obese Beagle dogs (28%-41% excess body weight) for an experimental high-protein medium-carbohydrate diet (protein level, 46% ME) and a commercial high-carbohydrate medium-protein diet (protein level, 24%ME) in obese dogs. Secondly, all the dogs were included in a weight loss programme. They were fed the high-protein medium-carbohydrate diet, and the energy allocation was gradually reduced until they reached their optimal body weight. Insulin sensitivity and body composition were evaluated before and after weight loss using a euglycaemic-hyperinsulinaemic clamp and the deuterium oxide dilution technique respectively. For statistical analysis, linear mixed effect models were used with a significance level of 5%. Postprandial plasma glucose and insulin concentrations were substantially lower with the high-protein medium-carbohydrate diet than the high-carbohydrate medium-protein diet. These differences can be explained mainly by the difference in carbohydrate content between the two diets. Energy restriction (35% lower energy intake than in the obese state) resulted in a 2.23±0.05% loss in body weight/week, and the dogs reached their optimal body weight in 12-16weeks. Weight loss was associated with a significant increase in insulin sensitivity. The high-protein medium-carbohydrate dietallowed fat-free mass preservation despite a relatively high rate of weekly weight loss. The increase in insulin sensitivity indicated improved control of carbohydrate metabolism, possible due to weight loss and to the nature of the diet. Thus, a high-protein medium-carbohydrate diet is a good nutritional solution for managing the weight of overweight dogs. This diet may improve glycaemic control, which could be beneficial for preventing or managing impaired glucose tolerance in obese dogs and for safe and successful weight loss while preserving lean body mass.

Effects of chromium supplementation on physiology, feed intake, and insulin related metabolism in growing pigs subjected to heat stress.

Improving insulin sensitivity may reduce impacts of heat stress (HS) in pigs by facilitating heat dissipation. Chromium (Cr) has been reported to improve insulin sensitivity in pigs. Therefore, the aim of this experiment was to investigate whether Cr supplementation can mitigate HS in growing pigs. Thirty-six gilts were randomly assigned to 2 diets containing 0 (control) or 400 ppb Cr. After 14 d the supplemented pigs were allocated to either 8 d thermoneutral (20°C constant; TN) or cyclic HS (35°C, 0900 h to 1700 h) conditions and continued their respective diet (n = 9 per group). Growth performance was recorded during the 14-d supplementation period. The physiological responses to HS were monitored by measuring respiration rate, rectal temperature, blood gas chemistry, and feed intake during thermal exposure. Kinetics of plasma glucose, insulin and NEFA were studied by intravenous glucose tolerance test (IVGTT) on d 8 of thermal treatment. Results showed Cr alleviated the HS-increased rectal temperature (P < 0.05) and respiration rate (P < 0.01) at 1300 h and 1600 h during thermal exposure. However, Cr did not mitigate the reduction in average daily feed intake which was reduced by 35% during HS or the HS-induced respiratory alkalosis. Chromium tended to increase average daily gain (0.86 vs. 0.95 kg, P = 0.070) during the 14-d supplementation under TN conditions before thermal exposure, which might be associated with the potential of Cr in improving overall insulin sensitivity, as evidenced by a reduced insulin resistance index calculated by Homeostatic Model Assessment (HOMA-IR; 0.65 vs. 0.51, P = 0.013) and a tendency of reduced fasting plasma insulin concentration (1.97 vs. 1.67 μU/mL, P = 0.094). Heat stress decreased the acute insulin releasing rate (P = 0.012) and consequently slowed glucose clearance rate (P = 0.035) during IVGTT. Besides, HS enlarged the values of area under the curve of NEFA during IVGTT (P < 0.01), indicating a reduced lipid mobilization. In conclusion, HS reduced insulin response to IVGTT. Chromium supplementation exhibited a potential in improving insulin sensitivity and mitigating HS symptoms in growing pigs.

Green tea extract does not affect exogenous glucose appearance but reduces insulinemia with glucose ingestion in exercise recovery.

We reported that supplementation with green tea extract (GTE) lowered the glycemic response to an oral glucose load following exercise, but via an unknown mechanism (Martin BJ, MacInnis MJ, Gillen JB, Skelly LE, Gibala MJ. Appl Physiol Nutr Metab 41: 1057-1063, 2016. Here we examined the effect of supplementation with GTE on plasma glucose kinetics on ingestion of a glucose beverage during exercise recovery. Eleven healthy, sedentary men (21 ± 2 yr old; body mass index = 23 ± 4 kg/m2, peak O2 uptake = 38 ± 7 ml·kg-1·min-1; means ± SD) ingested GTE (350 mg) or placebo (PLA) thrice daily for 7 days in a double-blind, crossover design. In the fasted state, a primed constant infusion of [U-13C6]glucose was started, and 1 h later, subjects performed a graded exercise test (25 W/3 min) on a cycle ergometer. Immediately postexercise, subjects ingested a 75-g glucose beverage containing 2 g of [6,6-2H2]glucose, and blood samples were collected every 10 min for 3 h of recovery. The rate of carbohydrate oxidation was lower during exercise after GTE vs. PLA (1.26 ± 0.34 vs. 1.48 ± 0.51 g/min, P = 0.04). Glucose area under the curve (AUC) was not different between treatments after drink ingestion (GTE = 1,067 ± 133 vs. PLA = 1,052 ± 91 mM/180 min, P = 0.91). Insulin AUC was lower after GTE vs. PLA (5,673 ± 2,153 vs. 7,039 ± 2,588 µIU/180 min, P = 0.05), despite similar rates of glucose appearance (GTE = 0.42 ± 0.16 vs. PLA = 0.43 ± 0.13 g/min, P = 0.74) and disappearance (GTE = 0.43 ± 0.14 vs. PLA = 0.44 ± 0.14 g/min, P = 0.57). We conclude that short-term GTE supplementation did not affect glucose kinetics following ingestion of an oral glucose load postexercise; however, GTE was associated with attenuated insulinemia. These findings suggest GTE lowers the insulin required for a given glucose load during postexercise recovery, which warrants further mechanistic studies in humans.

Effects of Rice Straw Supplemented with Urea and Molasses on Intermediary Metabolism of Plasma Glucose and Leucine in Sheep.

An isotope dilution method using [U-13C]glucose and [1-13C]leucine (Leu) was conducted to evaluate the effects of rice straw supplemented with urea and molasses (RSUM-diet) on plasma glucose and Leu turnover rates in sheep. Nitrogen (N) balance, rumen fermentation characteristics and blood metabolite concentrations were also determined. Four sheep were fed either mixed hay (MH-diet), or a RSUM-diet with a crossover design for two 21 days period. Feed allowance was computed on the basis of metabolizable energy at maintenance level. The isotope dilution method was performed as the primed-continuous infusion on day 21 of each dietary period. Nitrogen intake was lower (p = 0.01) for the RSUM-diet and N digestibility did not differ (p = 0.57) between diets. Concentrations of rumen total volatile fatty acids tended to be higher (p = 0.09) for the RSUM-diet than the MH-diet. Acetate concentration in the rumen did not differ (p = 0.38) between diets, whereas propionate concentration was higher (p = 0.01) for the RSUM-diet compared to the MH-diet. Turnover rates as well as concentrations of plasma glucose and Leu did not differ between diets. It can be concluded that kinetics of plasma glucose and Leu metabolism were comparable between the RSUM-diet and the MH-diet, and rumen fermentation characteristics were improved in sheep fed the RSUM-diet compared to the MH-diet.

ヒツジにおける消化機能，血漿グルコースおよびロイシン代謝に及ぼす飼料イネサイレージ給与の影響

飼料用イネの給与技術を確立するため，飼料イネサイレージ給与時における反芻家畜の消化機能および栄養素代謝を明らかにしようとした．実験にはヒツジ4頭を用いた．乾草と濃厚飼料（乾物重量比7：3）を維持代謝エネルギーの120%を給与する乾草区，乾草をそれぞれ穀粒型，茎葉型飼料イネサイレージで代替した穀粒区，茎葉区を設定した．窒素（N）出納，消化管内飼料滞留時間，第一胃内発酵性状，微生物態N供給量（MNS），血漿グルコース，ロイシン代謝を測定した．濃厚飼料の第一胃内通過速度は穀粒区が乾草区よりも高く（P<0.05），茎葉区は乾草区よりも低かった（P<0.05）．MNS,血漿グルコース，ロイシン代謝回転速度は飼料区間に差がなかった．以上のことから，穀粒型，茎葉型ともに飼料イネサイレージの給与は濃厚飼料の第一胃内通過速度などに影響を与えるが，ヒツジの栄養素代謝は乾草給与時と同等であることが示唆された．

The immediate effects of a single bout of aerobic exercise on oral glucose tolerance across the glucose tolerance continuum

We investigated glucose tolerance and postprandial glucose fluxes immediately after a single bout of aerobic exercise in subjects representing the entire glucose tolerance continuum. Twenty‐four men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or type 2 diabetes (T2D; age: 56 ± 1 years; body mass index: 27.8 ± 0.7 kg/m2, P > 0.05) underwent a 180‐min oral glucose tolerance test (OGTT) combined with constant intravenous infusion of [6,6‐2H2]glucose and ingestion of [U‐13C]glucose, following 1 h of exercise (50% of peak aerobic power) or rest. In both trials, plasma glucose concentrations and kinetics, insulin, C‐peptide, and glucagon were measured. Rates (mg kg−1 min−1) of glucose appearance from endogenous (RaEndo) and exogenous (oral glucose; RaOGTT) sources, and glucose disappearance (Rd) were determined. We found that exercise increased RaEndo, RaOGTT, and Rd (all P < 0.0001) in all groups with a tendency for a greater (~20%) peak RaOGTT value in NGT subjects when compared to IGT and T2D subjects. Accordingly, following exercise, the plasma glucose concentration during the OGTT was increased in NGT subjects (P < 0.05), while unchanged in subjects with IGT and T2D. In conclusion, while a single bout of moderate‐intensity exercise increased the postprandial glucose response in NGT subjects, glucose tolerance following exercise was preserved in the two hyperglycemic groups. Thus, postprandial plasma glucose responses immediately following exercise are dependent on the underlying degree of glycemic control.

Effects of Chinese herbal medicine on plasma glucose, protein and energy metabolism in sheep

BackgroundThe use of antibiotics in animal diets is facing negative feedback due to the hidden danger of drug residues to human health. Traditional Chinese herbal medicine has been used to replace antibiotics in the past two decades and played an increasingly important role in livestock production. The present study was carried out to assess the feeding effects of a traditional nourishing Chinese herbal medicine mixture on kinetics of plasma glucose, protein and energy metabolism in sheep. Ruminal fermentation characteristics were also determined.MethodsFour sheep were fed on either mixed hay (MH-diet) or MH-diet supplemented with 2% of Chinese herbal medicine (mixture of Astragalus root, Angelica root and Atractylodes rhizome; CHM-diet) over two 35-day periods using a crossover design. The turnover rate of plasma glucose was measured with an isotope dilution method using [U-13C]glucose. The rates of plasma leucine turnover and leucine oxidation, whole body protein synthesis (WBPS) and metabolic heat production were measured using the [1-13C]leucine dilution and open circuit calorimetry.ResultsBody weight gain of sheep was higher (P = 0.03) for CHM-diet than for MH-diet. Rumen pH was lower (P = 0.02), concentration of rumen total volatile fatty acid tended to be higher (P = 0.05) and acetate was higher (P = 0.04) for CHM-diet than for MH-diet. Turnover rates of plasma glucose and leucine did not differ between diets. Oxidation rate of leucine tended to be higher (P = 0.06) for CHM-diet than for MH-diet, but the WBPS did not differ between diets. Metabolic heat production tended to be greater (P = 0.05) for CHM-diet than for MH-diet.ConclusionsThe sheep fed on CHM-diet had a higher body weight gain and showed positive impacts on rumen fermentation and energy metabolism without resulting in any adverse response. Therefore, these results suggested that the Chinese herbal medicine mixture should be considered as a potential feed additive for sheep.