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The effects of neurotensin on the release of insulin, glucagon, and somatostatin were investigated in isolated pancreatic islets prepared from 3- to 4-day-old rats and maintained in culture for 48 h before use. Islets were incubated for 20 and 60 min in the presence of 3 or 23 mM glucose with or without neurotensin. In 20-min incubations at 3 mM glucose,(More)
The effect of the hypoglycaemic biguanide, metformin, on insulin binding and insulin action was investigated in rat hepatocyte monolayers. The binding of insulin was not modified in cultured cells exposed for 24 or 48 h to metformin at concentrations ranging from 1 mumol/l to 1 mmol/l, and no effect could be detected on insulin-induced down regulation.(More)
The effects of neurotensin on insulin and somatostatin release were examined in isolated pancreatic islets prepared from 3-4 days rats, and maintained in culture for 48 h before use. In the presence of 12 mM glucose, glucagon (50-2,000 ng/ml, i.e. 14-560 nM) caused a 2-fold increase in insulin and somatostatin release. Neurotensin (150 ng/ml, i.e., 100 nM)(More)
The enhanced ability of liver to extract glucogenic precursors from plasma in insulinopenic diabetes was investigated at the cellular level by measuring amino acid transport in isolated hepatocytes from streptozotocin-diabetes rats. The concentrative Na+-dependent uptake of alpha-amino[1-14C]isobutyric acid (AIB), a non-metabolizable analog of alanine, was(More)
The role of the insulin receptor carboxyl-terminal domain in regulation of insulin signal transduction was studied with antipeptide antibodies against the sequence 1321-1338, which contains two autophosphorylation sites, tyrosine 1328 and tyrosine 1334. The antibodies were introduced by electroporation in murine fibroblasts transfected with an expression(More)
In a previous report we described the properties of a rabbit anti-insulin receptor antibody (RAIR-IgG) and its effects on the autophosphorylation and kinase activity of human insulin receptors. The present study was carried out on the hepatoma cell line Fao. We tested the mimetic effects of RAIR-IgG on different biological parameters known to be stimulated(More)
Antibodies against peptides corresponding to sequences in the C-terminus of the insulin receptor beta-subunit were used to approach the putative role of this receptor domain in signal generation. Two sequences were chosen and correspond to peptide C1, comprising amino acids 1309-1326, and peptide C2, comprising amino acids 1294-1317. The two antibodies(More)
For the insulin receptor and the EGF receptor it is believed that ligand occupancy results in interactions within the heterotetrameric alpha 2 beta 2 insulin receptor or between monomeric EGF receptors. These interactions then activate the intracellular receptor tyrosine kinase which induces receptor autophosphorylation and phosphorylation of cellular(More)