Enhancement of insulin release and islet cell calcium content by an acyl-amino-alkyl benzoic acid derivative, HB 699

HB 699, a hypoglycaemic agent which lacks the structural requirements regarded as essential for the insulin releasing action of the sulfonamide group, was studied in isolated rat islets and compared with tolbutamide. In the presence of 8.3 mM glucose for long exposure (24 h) both substances induced an increase of insulin release without altering the islet insulin content. After preloading of the islets to isotopic equilibrium with 45Ca++ (24 h), HB 699 and tolbutamide induced a significant increase in total exchangeable calcium content parallelled by an increase in insulin release. Both effects could be suppressed by verapamil, a blocker of voltage-sensitive Ca++ channels. These results indicate that HB 699, like tolbutamide, stimulates insulin release by increasing Ca++ uptake by the B cells.     

Foregut morphology and ontogeny of the spider crab Maja brachydactyla (Brachyura,Majoidea, Majidae)

We describe the morphology of the foregut of the spider crab Maja brachydactyla Balss, 1922, from first larval stage to adult, with detailed stage‐specific documentation using light and scanning electron microscopy. A total of 40 ossicles have been identified in the foregut of adults of M. brachydactyla using Alizarin‐Red staining. The morphological pattern of the ossicles and gastric mill is very similar to other Majoidea species with only a few variations. The foregut of the zoeae stages appeared as a small and simple cavity, with a cardio‐pyloric valve that separates the stomach into cardiac and pyloric regions. The pyloric filter is present from the first zoea, in contrast to the brachyuran species which have an extended larval development. Calcified structures have been identified in the cardio‐pyloric valve and pyloric region of the zoeal stages. The most significant changes in foregut morphology take place after the metamorphosis from ZII to megalopa, including the occurrence of the gastric mill. In the megalopa stage, the foregut ossicles are recognizable by their organization and general morphology, but are different from the adult phase in shape and number. Moreover, the gastric teeth show important differences: the cusps of the lateral teeth are sharp (no molariform); the dorsal tooth have a small, dentate cusp (not a well‐developed quadrangular cusp); and the accessory teeth are composed of one sharp peak (instead of four sharp peaks). The gastric mill ontogeny from megalopa to adult reveals intermediate morphologies during the earlier juvenile stages. The relationship between gastric mill structures with food preferences and their contribution to the brachyuran phylogeny are briefly discussed. J. Morphol. 276:1109–1122, 2015. © 2015 Wiley Periodicals, Inc.     

Evidence for a role of exogenous or endogenous hyperlactatemia in insulin secretion in the dog.

Various types of experimental hyperlactatemia were induced in the normal anesthetized dog, and the changes in insulin secretion were measured in the pancreatico-duodenal vein. Hyperlactatemia was induced in the absence or in the presence of an infusion of sodium dichloroacetate (DCA), which activates pyruvate dehydrogenase. 1. Exogenous hyperlactatemia: The infusion of sodium L(+)lactate resulted in a strong increase in blood lactate level which was accompanied by a significant increase in the insulin output from the pancreatico-duodenal vein. The administration of DCA did not counteract the increase in lactate level and did not modify insulin output either. 2. Endogenous hyperlactatemia: This was induced either by pharmacological means: the subcutaneous injection of an antidiabetic biguanide, phenformin (20 mg/kg), or by physiological means: intense muscular work. In both cases an increase in the lactate level and in insulin output was recorded. The administration of DCA suppressed the hyperlactatemia and counteracted the increase in insulin output. These results show that there is a relationship between lactate level and insulin secretion, and give evidence for a role of endogenous lactate in the regulation of insulin secretion.