Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of cyclic adenosine 3',5'-monophosphate (cAMP) in the regulation of rat liver bilirubin uridine diphosphate glucuronyltransferase (UDP-GT) was studied. Augmentation of UDP-GT activity was obtained by cAMP, but not by 3'-AMP. A single administration of glucagon initiated a rapid but limited increase in enzyme activity, which reached a maximum after 2 hr. Similar augmentation of the hepatic enzyme was produced by injection of N6,O2-dibutyryl cAMP. The nucleotide is the mediator for UDP-GT augmentation by glucagon. The injection of glucagon led within 20 min to a 40-fold increase in the concentration of cAMP. The augmentation of UDP-GT activity by glucagon or dibutyryl cAMP was fully inhibited by actinomycin D. A second stimulation of liver by glucagon or dibutyryl cAMP 4 hr after the first injection, produced a new increase of UDP-GT activity.
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PMID:Augmentation of uridine diphosphate glucuronyltransferase activity in rat liver by adenosine 3',5'-monophosphate. 21 84

This study was aimed to elucidate whether GDP can mediate hormonal signal to adenylate cyclase in hepatic glucagon sensitive adenylate cyclase with ATP as substrate. Conversion of added GDP to GTP catalyzed by nucleoside diphosphate kinase was suppressed to less than 0.3% of added GDP by including UDP. Inhibition of this enzyme activity by UDP was accompanied by a preferential loss of the stimulatory effect of glucagon plus GDP on cyclase activity without changes in effects of glucagon plus GTP, glucagon plus guanosine 5'-(beta, gamma-imino)triphosphate, and NaF. Under this condition, i.e. in the presence of UDP, GDP competitively inhibited the actions of GTP (Ki for GDP, 1 microM) and guanosine 5'-(beta, gamma-imino)triphosphate in the presence of glucagon, the inhibition being complete at high GDP concentrations. GDP also inhibited cyclase activity stimulated by NaF with UDP but did only slightly without UDP. It was demonstrated that nucleoside diphosphate kinase is located in membranes in addition to cytosol fraction. However, the activity of membrane-associated enzyme was not affected by the addition of glucagon. Based on these observations, it is concluded that GDP is unable to mediate hormonal signal to adenylate cyclase and that it acts as an inhibitor of cyclase activity stimulated by GTP or its analog along with hormone. The results suggest a possible role of membrane-associated nucleoside diphosphate kinase in determining GTP and GDP levels at or near their binding site so as to replenish GTP and, thereby, decrease the inhibitory action of GDP when hormone is present.
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PMID:GDP does not mediate but rather inhibits hormonal signal to adenylate cyclase. 629 38

Various metabolic studies were performed in a patient with the idiopathic Fanconi syndrome in whom constant ketonuria suggested that organic acidemia might contribute to the metabolic acidosis. Glucose intolerance with a diminished insulin release was found after PO or IV glucose loads and after glucagon administratio. An insulinopenic "diabetes-like" state has not previously been described in such patients. The patient had impaired galactose-glucose interconversion, elevated blood lactate levels, reduced pyruvate levels, and an increased lactate:pyruvate ratio. Hepatomegaly and hypoglycemia were not present, and liver and muscle biopsies revealed no enzymatic evidence of glycogenosis. The erythrocyte UDP galactose transferase activity was normal. The patient failed to convert fructose to glucose and had a rise in blood lactate after ethanol administration. Further studies revealed no production of glucose after alanine or glycerol administraion, each test being associated with elevated blood lactate levels and, after alanine, an increased lactate:pyruvate ratio. The lactate:pyruvate ratio was elevated after glucagon administration with increased lactate and reduced pyruvate concentrations.
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PMID:Abnormalities of carbohydrate metabolism in idiopathic Fanconi syndrome. 738 41

Fluxes through intrahepatic glucose-producing metabolic pathways were measured in normal humans during overnight or prolonged (60 h) fasting. The glucuronate probe was used to measure the turnover and sources of hepatic UDP-glucose; mass isotopomer distribution analysis from [2-13C1]glycerol for gluconeogenesis and UDP-gluconeogenesis; [U-13C6]glucose for glucose production (GP) and the direct UDP-glucose pathway; and [1-2H1]galactose for UDP-glucose flux and retention in hepatic glycogen. After overnight fasting, GP (fluxes in milligram per kilogram per minute) was 2.19+/-0.09, of which 0.79 (36%) was from gluconeogenesis, 1.40 was from glycogenolysis, 0.30 was retained in glycogen via UDP-gluconeogenesis, and 0.17 entered hepatic UDP-glucose by the direct pathway. Thus, total flux through the gluconeogenic pathway (1.09) represented 54% of extrahepatic glucose disposal (2.02) and the net hepatic glycogen depletion rate was 0.93 (46%). Prolonging [2-13C1]glycerol infusion slowly increased measured fractional gluconeogenesis. In response to prolonged fasting, GP was lower (1. 43+/-0.06) and fractional and absolute gluconeogenesis were higher (78+/-2% and 1.11+/-0.07, respectively). The small but nonzero glycogen input to plasma glucose (0.32+/-0.03) was completely balanced by retained UDP-gluconeogenesis (0.31+/-0.02). Total gluconeogenic pathway flux therefore accounted for 99+/-2% of GP, but with a glycogen cycle interposed. Prolonging isotope infusion to 10 h increased measured fractional gluconeogenesis and UDP-gluconeogenesis to 84-96%, implying replacement of glycogen by gluconeogenic-labeled glucose. Moreover, after glucagon administration, GP (1.65), recovery of [1-2H1]galactose label in plasma glucose (25%) and fractional gluconeogenesis (91%) increased, such that 78% (0.45/0.59) of glycogen released was labeled (i.e., of recent gluconeogenic origin). In conclusion, hepatic gluconeogenic flux into glycogen and glycogen turnover persist during fasting in humans, reconciling inconsistencies in the literature and interposing another locus of control in the normal pathway of GP.
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PMID:Hepatic gluconeogenic fluxes and glycogen turnover during fasting in humans. A stable isotope study. 927 49

The effect of two culture configurations (single collagen gel and double collagen gel) and of two hormones (insulin and glucagon) on the differentiated status and the intracellular nucleotide pools of primary porcine hepatocytes was investigated. The objective was to analyze and monitor the current state of differentiation supported by the two culture modes using intracellular nucleotide analysis. Specific intracellular nucleotide ratios, namely the nucleoside triphosphate (NTP) and the uridine (U) ratio were shown to consistently reflect the state of dedifferentiation status of the primary cells in culture affected by the presence of the two hormones insulin and glucagon. Continuous dedifferentiation of the cells was monitored in parallel by the reduction of the secretion of albumin, and changes in UDP-activated hexoses and UDP-glucuronate. The presence of insulin maintained the differentiated status of hepatocytes for more than 12 days when cultivated under double gel conditions whereas glucagon was less effective. In contrast, cells cultivated in a single gel matrix immediately started to dedifferentiate upon seeding. NTP and U ratios were shown to be more sensitive for monitoring dedifferentiation in culture than the albumin secretion. Their use allowed the generation of an easily applicable NTP-U plot in order to give a direct graphical representation of the current differentiation status of the cultured cells. Moreover, the transition from functional and differentiated hepatocytes to dedifferentiated fibroblasts could be determined earlier by the nucleotide ratios compared to the conventional method of monitoring the albumin secretion rate.
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PMID:Intracellular nucleotide pools and ratios as tools for monitoring dedifferentiation of primary porcine hepatocytes in culture. 1900 82