Showing papers by "Rüdiger Göke published in 1991"

Glucagon-like peptide-1(7-36) amide is a new incretin/enterogastrone candidate.

Abstract: Cloning and sequence analysis of cDNAs and DNA fragments from genomic libraries has led to a dramatic increase in understanding of the glucagon-related peptides in recent years. The primary structure of the biosynthetic precursor of glucagon (preproglucagon) has been elucidated. The complex structural connec- tions between the multiple molecular forms of the glucagon-like peptides in tissues and in the circulation have been determined [ 1,2]. Mammalian proglucagon consists of 160 amino acid residues and is synthesized in the islets of Langerhans, intestine and brain. An exciting recent finding is that in addition to glucagon the preproglucagon gene in mammals encodes two additional peptides with struc- tural similarity to glucagon, termed glucagon-like peptide-1 and -2 (GLP-I and GLP-2). The truncated form of GLP-1, GLP-1(7-36) amide, which is secreted by the mammalian intestine, strongly stimulates insu- lin secretion and inhibits gastric acid secretion. This review focuses mainly on the truncated form of GLP-1. since a rapidly increasing number of reports indicate a remarkable interest of investigators in this particular hormone, which actually fulfills the classical role of an ‘enterogastrone’ and ‘incretin’ hormone. The purpose here is to describe what is known so far about the origin, processing, organ distribution and actions of this peptide and to search for promising future direc- tions of further investigations.

CCK receptor antagonist loxiglumide alters uptake of CCK in perfused liver and pancreatic acini of the rat.

Abstract: The aim of the present study was to analyze the effect of the specific cholecystokinin (CCK) receptor antagonist loxiglumide on hepatic and pancreatic processing of CCK-8 and the CCK analogue cerulein. Rat liver perfusion was performed in a non-recirculating system. CCK concentrations were measured by radioimmunoassay in perfusates from the inflow cannula (portal vein) and the outflow cannula (hepatic vein). In rat pancreatic acini, the effect of loxiglumide on internalization and surface-binding of radiolabelled CCK-8 was determined. Cerulein (20 nM, 2 nM) was extracted in a single pass through the liver by 29.7 and 25.4%, respectively. The hepatic uptake of CCK-8 (50 pM, 2 nM) was more than 90 and 89.9%, respectively. Loxiglumide drastically inhibited hepatic extraction of both peptides and reduced internalization of 125I-CCK-8 in pancreatic acini dose dependently by 39-93%. These results demonstrate that the potent CCK receptor antagonist loxiglumide significantly decreased CCK uptake by the liver and pancreas.

Helodermin and islet hormone release in isolated rat pancreas.

Abstract: The effect of helodermin (1,10,100 pmol/L), a new member of the VIP/ secretin/glucagon peptide family, was investigated in glucose- (10 mmol/L) and arginine- (10 mmol/L) induced insulin, glucagon, and somatostatin secretion from the isolated perfused rat pancreas Helodermin stimulated the somatostatin release in a concentration-dependent manner during the first (controls, 100%; 1 pmol/L, 113%, ns; 10 pmol/L, 175%,p<005; 100 pmol/L, 233%,p<005) and the second secretion phases (controls, 100%; 1 pmol/L, 117%, ns; 10 pmol/L, 210%, p<005; 100 pmol/L, 362%,p<005) There was a biphasic glucagon response with an inhibition during the first phase (controls, 100%; 1 pmol/L, 92%; 10 pmol/L, 63%,p<005; 100 pmol/L, 52%,p<005%) and a stimulation during the second phase (controls, 100%; 1 pmol/L, 117%, ns; 10 pmol/L, 210%, p<005; 100 pmol/L, 362%, p<005) Helodermin had weak stimulatory effects on pancreatic beta cells with a maximum at 10 pmol/L (first phase: controls, 100%; 1 pmol/L, 96%, ns; 10 pmol/L, 148%,p<005; 100 pmol/L, 136%, ns; second phase: controls, 100%; 1 pmol/L, 104%, ns; 10 pmol/L, 170%,p<005; 100 pmol/L, 136%, ns)