Pancreatic insulin secretion following intrapancreatic infusion of amino acid

Selective in situ pancreatic perfusion via chronic in vivo celiac artery catheterization

A new technique to catheterize the celiac artery has been developed. This has opened the possibility for direct in vivo, in situ study of pancreatic endocrine cell function in a conscious experimental animal. The catheter is small, soft and placed without arterial ligation so that celiac artery, hepatic, splenic, and pancreatic blood flows were essentially not compromised. Arterial vessel integrity, absence of inflammation, and thrombosis as well as catheter patency were achieved for periods exceeding eight months. Metabolically and hormonally, the presence of the catheter had no effect on the fasting status. However, we found somewhat lower glucose levels and higher insulin levels in the response to oral glucose challenges after catheterization, but these differences were statistically not significant. Glucose loads of 50 mg/kg (0.75 g) administered directly to the pancreas via the celiac artery produced peak insulin levels similar to peripheral glucose loads some tenfold larger. We suggest that this technique may be useful to selectively study the first-pass pancreatic response to a variety of hormones, drugs or metabolic substrates.

Hepatic-portal nutrient infustion: effect on feeding in intact and vagotomized rabbits

Hepatic-portal infusions of isotonic glucose did not influence food intake in free-feeding rabbits. In contrast, several other macronutrients and some of their metabolites, infused via the same route, cause anorexia followed by prolonged hypophagia. Its duration was generally decreased when the same infusions were performed during the nocturnal period. Vagotomy did not significantly alter the food intake responses to hepatic-portal infusions of either glucose or the other experimental substances. The results of related experiments have demonstrated that prolonged anorexia was not a consequence of the fast infusion rate or the generalized behavioral mallaise. However, when the infusions of most anorexigenic substances were followed by intraperitoneal administration of insulin, the duration of anorexia was shortened and food consumption was elevated. The results provided indirect evidence for the vagally mediated regulatory contribution of the previously studied neural and humoral intestinal mechanisms which are bypassed by infusing nutrient loads directly into the hepatic-portal circulation.