Physiological Parameter Values for Physiologically Based Pharmacokinetic Models

Transjugular intrahepatic portosystemic shunts: Comparison with paracentesis in patients with cirrhosis and refractory ascites: A randomized trial

Transcutaneous Doppler ultrasound was used to assess the effects of exercise on both fasting and postprandial superior mesenteric artery blood flow. After treadmill exercise (speed 5 km/h, gradient 20%, duration 15 min) in 16 subjects, superior mesenteric artery blood flow decreased by 43% immediately after the end of the exercise and by 29% at five minutes and 24% at 10 minutes postexercise. The superior mesenteric artery blood flow response to a combination of a treadmill exercise and a liquid meal in 15 volunteers was significantly smaller at five minutes from the end of the stimuli, than the response to the meal alone (15 controls) (635 +/- 51 ml/min v 846 +/- 72 ml/min) (p less than 0.025), but not different at any other time. Thus exercise reduces mesenteric blood flow in both the fasting and postprandial state in normal subjects.

https://gut.bmj.com/content/gutjnl/28/5/583.full.pdf

Effects of exercise on mesenteric blood flow in man.

The present study was designed to determine the quantitative effects of starchy meals containing guar gum on rates of net apparent glucose absorption and net apparent insulin and gastric inhibitory polypeptide (GIP) production in growing pigs. The effects of these meals on the viscosity of jejunal digesta were also examined and correlated to changes in glucose absorption. Four growing pigs were each given either a low-fat semi-purified diet (control) or the same diet supplemented with a high-molecularweight par gum at concentrations in the diet of 20 or 40g/kg. Blood samples were removed simultaneously via indwelling catheters from the mesenteric artery and the hepatic portal vein. Samples of jejunal digesta were removed via a T-piece cannula and used immediately for viscosity measurements at 39’. The ‘zero-shear’ viscosity of each sample was then calculated. Blood-flow measurements were made using an ultrasonic flow probe fitted to the hepatic portal vein. All measurements were made at intervals of 10 or 30 min during a 4 h postprandial period. Meals containing guar gum significantly increased (P < 0.05) the viscosity of jejunal digesta, an effect that was strongly dependent on the concentration of guar gum in the original diet. No significant differences in blood-flow rates were found between the control and guar-containing diets. Both concentrations of guar gum significantly reduced (P < 0.05) glucose absorption and insulin and GIP secretion rates over the 4 h postprandial period. An inverse relationship between the rate of glucose absorption and the ‘zero-shear’ viscosity of jejunal digesta was found. This study also provides direct evidence for the important role played by the enteroinsular axis in modifying the glycaemic response to a meal containing guar gum. Guar gnm: Nutrient absorption: Viscosity: Pig

/pdf/the-effect-of-high-molecular-weight-guar-gum-on-net-apparent-53gi7s3nuu.pdf

The effect of high-molecular-weight guar gum on net apparent glucose absorption and net apparent insulin and gastric inhibitory polypeptide production in the growing pig : relationship to rheological changes in jejunal digesta

https://www.journal-of-hepatology.eu/article/S0168-8278(05)80660-9/pdf

Value of measurement of mean portal flow velocity by Doppler flowmetry in the diagnosis of portal hypertension

A duplex scanner which consists of a real time two dimensional scanner and a pulsed Doppler flowmeter was used to measure superior mesenteric blood flow in 70 healthy subjects. By processing the Doppler shift signals, the instantaneous average Doppler shift frequency and then the instantaneous average velocity of the flow rate were calculated. Both diameter of the vessel and angle between vessel and beam were measured from real time imaging. The mean (+/- standard error of the mean) of the superior mesenteric blood flow was 517 +/- 19 ml/min. There was neither significant difference in flow between sexes, nor correlation between flow and age (r = 0.042). The mean of coefficients of variability were 6.8% over the short term, and 8.2% in long term studies.

https://gut.bmj.com/content/gutjnl/27/1/100.full.pdf

Transcutaneous Doppler ultrasound measurement of superior mesenteric artery blood flow in man.

The volume flow rate of blood in the portal vein was measured using a duplex ultrasound system. The many errors inherent in the duplex method were assessed with particular reference to the portal vein and appropriate correction factors were obtained by in vitro calibration. The effect of posture on flow was investigated by examining 45 healthy volunteers in three different positions; standing, supine and tilted head down at 20 degrees from the horizontal. The mean volume blood flow in the supine position was 864 (188)ml/min (mean 1SD). When standing, the mean volume blood flow was significantly reduced by 26% to 662 (169)ml/min. There was, however, no significant difference between flow when supine and when tilted head down at 20 degrees from the horizontal.

https://gut.bmj.com/content/gutjnl/30/4/503.full.pdf

Measurement of normal portal venous blood flow by Doppler ultrasound.

Transcutaneous Doppler ultrasound was used to measure coeliac axis blood flow in 42 normal subjects in the fasting state and in 10 subjects following a liquid meal. A Duplex scanner was used and coeliac axis blood flow was estimated by calculating the instantaneous average velocity of blood flow over the cardiac cycle. Both the diameter of the vessel and the angle between the vessel and the beam were measured from real time imaging. The mean (+/- s.e.m.) of coeliac axis blood flow was 703 +/- 24 ml/min. There was no difference in the results between the sexes nor any correlation between flow and age. The mean coefficient of variability was 7.8 per cent in a 1 day test and 9.2 per cent in a 2 day test. Coeliac axis blood flow increased by 38 per cent immediately after the end of ingestion of the meal and declined to 29 per cent 5 min and 24 per cent 10 min later.

J. M. Evans

Papers

Transcutaneous Doppler ultrasound measurement of superior mesenteric artery blood flow in man.

Measurement of normal portal venous blood flow by Doppler ultrasound.

Transcutaneous Doppler ultrasound measurement of coeliac axis blood flow in man.