Metabolic and hormonal effects of test meals with various protein contents in pigs

Abstract

The postprandial release of immunoreactive insulin, glucagon, gastrin, somatostatin, pancreatic polypeptide (PP), and gastric inhibitory polypeptide (GIP) was studied in parallel with the absorption of sugars and amino acids in conscious pigs. Six pigs fitted with permanent catheters in the portal vein and arterial blood system as well as within an electromagnetic flow probe around the portal vein received successively at 3-day intervals, three meals of 800 g each containing 0, 14, or 28% protein (semisynthetic diets based on fish protein). Blood samples were collected and portal blood flow was recorded during a postprandial period of 8 h. For the same level of feed intake, an increase in the dietary protein concentration led to a higher alpha-amino nitrogen absorption and to a lower appearance of reducing sugars in the portal vein; in addition, the carbohydrate absorption efficiency (amounts absorbed as a percentage of amounts ingested) was reduced, showing the competition between the absorption of amino acids and glucose. The largest absorption occurred during the first 4 h after the meal, but neither the digestion of proteins nor that of carbohydrates were finished 8 h after the meal since portoarterial differences could still be observed. All test meals induced a rise of portal and peripheral concentrations of insulin, gastrin, somatostatin, and PP, and of the systemic level of GIP. Glucagon increased after the 28% protein meal only. The rise of plasma insulin paralleled that of blood glucose, and bore a significant positive relationship to the systemic GIP level in the early postprandial period. In terms of absolute amounts, portoarterial concentration gradients increased postprandially. Insulin release was significantly the highest after intake of the 14% protein diet. The gastrin response was significantly correlated to the amount of protein. Similarly the release of glucagon and somatostatin tended to increase with increasing dietary amount, but differences failed to reach significance (P less than 0.05), except for glucagon 2 h after the meal. There were very close relationships between the hourly amounts of alpha-amino nitrogen absorbed and gastrin and glucagon production, as between insulin and PP secretions. From the present results, the induction of physiological increments of plasma peptide concentration in 60-kg pigs would require infusion rates of about 50-250 micrograms/h for insulin, 1-4 micrograms/h for gastrin 17, 5-10 micrograms/h for glucagon and somatostatin, and 5-50 micrograms/h for PP.

The relationships between glucose absorption and insulin secretion and the migrating myoelectric complex in the pig

“…During glucose infusion only 75 % of the glucose infused appeared in the portal vein. Assuming the blood flow estimates are correct -values agree well with values obtained in the pig by Rerat, Chayvialle, Kande, Vaissade, Vaugelade & Bourrier (1985) -and that little glucose is carried by the erythrocytes in the pig (Kim & McManus, 1971), the difference must represent the amount of glucose metabolized by the portal drained viscera. Rerat, Vaissade & Vaugelade (1984) estimated that the intestinal wall metabolized 14 4 g glucose h-' after feeding in pigs of approximately the same weight as in this experiment.…”

The effect of portal and peripheral insulin delivery on carbohydrate and lipid metabolism in a miniature pig model of human IDDM

“…Anaesthesia was induced in the minipigs after an overnight fast, by intramuscular injection of ketamine (10.0 mg ⋅ kg − 1 ; Ketalar, Parke Davis, Eastleigh, UK) and diazepam emulsion (2.0 mg ⋅ kg − 1 ; Diazemuls, Dumex, Aylesbury, UK) and was maintained by inhalation of 1-2 % isoflurane (Abbot, Maidenhead, UK) in oxygen (6-8 litres ⋅ min − 1 ). Under anaesthesia, polyurethane catheters (16 G, 150 mm; Secalon Universal Ohmeda, Swindon, UK) were inserted into the carotid artery and jugular and portal veins using established procedures [41]. Cefuroxime (Zinacef 250 mg, i. v.; Glaxo, Greenford, UK) was administered immediately before and for 48 h post-operatively.…”

Non-starch polysaccharides extracted from seaweed can modulate intestinal absorption of glucose and insulin response in the pig

“…: 1.27 mm, o.d. : 2.29 mm, Tygon Norton, Cleveland, OH, USA) in the portal vein (PV) and in the right carotid artery (CA), as described previously [25,32], and with an ultrasonic portal blood-flow probe (12 or 14 mm probe, Transonic Systems Ltd, Ithaca, NY, USA). Carotid artery cannulation, allowing to sample blood from the thoracic aorta, has been reported to be the best technique to obtain systemic arterial blood in the pig [33].…”