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 direct effects of porcine insulin and glucagon on bone collagen and non-collagen protein synthesis have been examined in cultures of calvaria obtained from 21-day fetal rats. Bones were incubated for 24 to 96 h and [3H]proline was added for the last 2 h of culture. Incorporation of the label into collagenase-digestible protein (CDP) and noncollagen protein (NCP) was determined using purified bacterial collagenase. Insulin increased the labeling of CDP by 60 to 115% at concentrations of 10(-9) to 10(-6) M. A smaller stimulatory effect was observed on NCP. The effect on CDP appeared after 12 to 24 h of culture, was maintained for 96 h in the continuous presence of the hormone, but was lost within 3 h of removal of insulin from the culture medium. Insulin appeared to have a direct effect on collagen synthesis and not on collagen breakdown. Insulin did not affect the incorporation of [3H]uridine or [3H]thymidine into the RNA and DNA fractions of bone at 24 h. Insulin opposed the inhibitory effects of parathyroid hormone and dibutyryl cyclic-3',5'-adenosine monophosphate and to a lesser extent, the inhibitory effect of isobutylmethylxanthine on the labeling of CDP. Glucagon did not affect the response to insulin and by itself had small and variable inhibitory effects on proline incorporation.
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PMID:Hormonal control of bone collagen synthesis in vitro. Effects of insulin and glucagon. 40 59

Parenchymal cells from adult rat liver, isolated by a collagenase perfusion technique, have been maintained in primary culture and a detailed study on carbohydrate metabolism carried out over the initial 48-hour culture period. The glucose concentration of the medium exerts a major influence on glycogen accumulation by the cells. Insulin, particularly at high glucose concentrations, stimulates glycogen biosynthesis, whereas glucagon prevents glycogen accumulation. Dexamethasone was without effect on glycogen metabolism. Glucose appears to stimulate glycogen accumulation by activation of glycogen synthetase enzyme. However, there is a gradual loss of synthetase activity throughout the culture period. Similar decreases in activity were noted for pyruvate kinase, aldolase and hexokinase. Glucose, insulin and dexamethasone were unable to prevent these decreases in enzyme activity. Foetal bovine serum contains fructose and this hexose appears to be the factor in serum which is responsible for the activation of glycogen accumulation in the presence of physiological glucose concentrations. The lactic acid content of the serum may also stimulate glycogen accumulation. In general, there is a gradual loss of the pattern of carbohydrate metabolism typical of differentiated hepatocytes during the culture period.
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PMID:Effects of hormones and serum on glycogen metabolism in adult rat liver parenchymal cell primary cultures. 40 98

Liver parenchymal cells were isolated from adult rats by digesting liver slices or perfusing liver with collagenase. The cell yields were 1.5 X 10(7) and 1.0 X 10(8) cells/g liver from slices and perfused liver, respectively, and in both cases the cell viabilities and attachment efficiencies were over 90% and 60%, respectively. The cells were viable for more than one week when cultured in Williams medium E with 10% fetal bovine serum, and addition of insulin and dexamethasone enhanced the maintenance of cell viability. Various biochemical functions or freshly isolated cells and cultured cells were compared in this medium. In freshly isolated cells, induction of tyrosine transaminase [EC 2.6.1.5] by dexamethasone was low and none of the hormones examined stimulated protein synthesis; but when the cells had been cultured for a few days, induction of tyrosine transaminase became prominent, and insulin and dexamethasone stimulated protein synthesis and glucagon inhibited their effect. About half the synthesized proteins were secreted into the medium and among these proteins, albumin, transferrin, fibrinogen, and lipoproteins were identified immunochemically and electrophoretically. It was also shown that the polysomes in freshly isolated cells were almost completely disaggregated, but that in cells after a few days culture they were reaggregated. These results showed that freshly isolated cells have impaired functions, but that after culture for a few days the cells recover various liver functions and thus become more suitable for use in biochemical studies on liver functions.
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PMID:Biochemical studies on liver functions in primary cultured hepatocytes of adult rats. I. Hormonal effects on cell viability and protein synthesis. 71 6

This work was undertaken to study the effect of prednisolone on glucagon release in mouse pancreatic islets isolated by the collagenase technique. Pretreatment of the donors with prednisolone (0.2--0.3 mg daily) induced an increase in glucagon release both in the absence (1005+/-75, SEM, vs. 796+/-46 pg/10 islets/60 min, p=0.019) and in the presence of 7.5 mM arginine (1500+/-119 vs. 1236+/-61 pg/10 islets/60 min, p=0.05). The glucagon content of the islets was not modified by the treatment (28.6+/-1.1 vs. 28.0+/-1.1 ng/50 islets). The addition of prednisolone (5 - 10(-5) M) into the medium, failed to affect significantly glucagon secretion. In agreement with previous human studies, our data indicate that chronic glucocorticoid administration augments the secretory activity of the A-cell. This does not seem to be a result of increased glucagon synthesis nor a direct effect of glucocorticoids on the glucagon-releasing mechanism. Rather, environmental changes induced by these hormones could be responsible for A-cell hyperfunction.
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PMID:Enhanced glucagon secretion by pancreatic islets from prednisolone-treated mice. 78 66

1. Rat livers were dissociated into their constituent cells by perfusion through the portal vein with a medium containing collagenase, and hepatocytes separated from non-parenchymal cells. 2. It is shown that the procedure described by Wisher & Evans [(1975) Biochem. J. 146, 375-388] for preparation of plasma membranes from liver tissue when applied to isolated hepatocytes also yielded subfractions of similar morphology and marker-enzyme distribution. 3. Thus the distribution of alkaline phosphodiesterase, 5'-nucleotidase and the basal and glucagon-stimulated adenylate cyclase among two 'light' vesicular and one 'heavy' junction-containing plasma-membrane subfractions paralleled that reported for tissue-derived plasma-membrane subfractions. 4. Increased recoveries and specific activities of plasma-membrane marker enzymes were obtained when soya-bean trypsin inhibitor was included in the collagenase-containing perfusion media used to dissociate the liver. 5. Polyacrylamide-gel-electrophoretic analysis of the corresponding plasma-membrane subfractions prepared from liver tissue and isolated hepatocytes were generally similar. 6. The results indicate that the functional polarity of the hepatocyte's plasma membrane is retained after tissue dissociation. The damage occurring to plasma-membrane ectoenzymes by the collagenase-perfusion procedure is discussed.
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PMID:Preparation of plasma-membrane subfractions from isolated rat hepatocytes. 88 Feb 46

1. Isolated lamb liver cells were prepared from 24-h-starved animals by venous perfusion of the excised caudate lobe with buffer containing collagenase. On the basis of Trypan-Blue exclusion, rate of O2 uptake, adenine nucleotide content and retention of constitutive enzymes, these cells were judged to be intact. 2. Isolated caudate-lobe liver cells showed rates of gluconeogenesis from 10 mM-propionate and 10 mM-lactate that compared favourably with rates determined in isolated median-lobe cells and with rates determined with the isolated perfused lamb liver. 3. The gluconeogenic potential of substrates tested depended on the lamb's age. Cells prepared from suckling lambs (up to 20 days of age and essentially non-ruminant) showed highest rates from galactose, serine and alanine; those prepared from post-weaned lambs (older than 30 days of age and ruminant) showed highest rates from propionate, lactate and fructose. 4. Gluconeogenic rates from endogeneous precursors, 10 mM-propionate and 10mM-galactose, were linear for 1 h and were both stimulated by 1 muM-glucagon. Provided the endogenous rate of gluconeogenesis remained unchanged after substrate addition, glucagon caused a net stimulation of gluconeogenesis from each of these substrates. 5. Gluconeogenic capacity and glucagon sensitivity were examined in cells maintained in substrate-free oxygenated buffer at 37 degrees, 22 degrees and * degrees C. Even under the best of the three conditions of storage that were tested (i.e. at 22 degrees C in gelatin-containing buffer) deterioration of the lamb cells proceeded rapidly, and loss of glucagon responsiveness preceeded the loss of ability to convert precursor into glucose. 6. n-Butyric acid, 2-methylpropanoic acid and 3-methylbutanoic acid at concentrations comparable with those found in lamb portal-vein blood each stimulated gluconeogenesis from 10mM-galactose or 10mM-propionate; gluconeogenesis from galactose was stimulated to the greater extent. 7. The regulatory effects of glucagon and sodium butyrate on lamb liver-cell gluconeogenesis and glycogenolysis were compared. Glucagon (1 muM) and 2mM-butyrate accelerated the rate of glucose formation of liver cells of 24h-starved animals from lactate+pyruvate or fructose. Insulin (20nM) decreased both gluconeogenesis and the efficacy of 1 muM-glucagon. For lactate+pyruvate as substrate, the stimulatory effect of butyrate was additive to that of 1muM-glucagon and for both lactate+pyruvate and fructose the stimulatory effect of butyrate was not influenced by 20nM-insulin. In contrast with glucagon, which stimulated the rate of glycogenolysis in cells prepared from fed lambs, butyrate (0.1-20mM) had no effect. 8. It is concluded that glucagon and butyrate stimulate lamb liver-cell gluconeogenesis by different mechanisms.
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PMID:Gluconeogenesis in isolated intact lamb liver cells. Effects of glucagon and butyrate. 94 49

Adipose tissue was removed from five-day old chickens after a) an overnight fast, b) total pancreatectomy and c) partial evisceration and digested with collagenase. The adipocytes were incubated with pancreatic glucagon (Novo) and the glycerol released into the medium taken as the index of lipolytic activity. A moderate fast, while being without effect on basal lipolysis, slightly decreased adipocyte sensitivity to glucagon. Pancreatectomy and evisceration significantly reduced both basal lipolysis and the response to glucagon: the impairment was most evident just at the concentration found in the plasma of such operated animals. It seems clear that normal lipolysis is under the control not only of pancreatic factors, but also of those of intestinal origin, and can only proceed normally when both are present.
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PMID:The contribution of the pancreas and the intestine to the regulation of lipolysis in birds. 2. Impaired lipolytic activity of pancreatic glucagon in the absence of either the pancreas or the intestine in the chicken. 97 34

Perfusion of growth hormone inhibitory factor (somatostatin) into rat pancreas inhibited secretion of glucagon and insulin into medium containing 5.5 mM glucose. A 15-min infusion of arginine (20 mM) greatly increased glucagon and insulin secretion. When perfused simultaneously with arginine, somatostatin (55 nM) abolished the increase in glucagon secretion. The acute phase of insulin secretion in response to arginine was attenuated by somatostatin, and subsequent secretion was decreased to control levels. Pretreatment for 5 min with somatostatin blocked even acute-phase insulin secretion in response to arginine. Somatostatin did not affect basal or glucose-stimulated secretion of insulin from rat pancreatic islets isolated by the collagenase technique. Arginine-stimulated secretion of insulin was enhanced by somatostatin in isolated islets. These results demonstrate a direct effect of somatostatin on the pancreas to inhibit secretion of glucagon and insulin. The failure of somatostatin to inhibit insulin secretion in pancreatic islets may be due to alterations in the beta cells produced by the isolation procedure. It is also possible that the effect of somatostatin on insulin secretion may be mediated indirectly.
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PMID:Inhibition of glucagon and insulin secretion by somatostatin in the rat pancreas perfused in situ. 108 35

Viable pancreatic islets were isolated from the pancreas of humans using modifications of the collagenase digestion and Ficoll gradient techniques. Gel filtration of tissue extracts following islet incubation in the presence of 3H- tryptophan indicated that radioactivity becomes incorporated into at least two islet proteins. The larger of the two (LGI) has the approximate molecular size of proinsuiln and the smaller coelutes with glucagon as determined by column standardization. Radioimmunoassay of the gel filtration eluate for glucagon revealed that both molecules have glucagon immunoreactivity. Gel filtration in the presence of 8M urea did not alter the elution pattern of the LGI molecule. Polyacrylamide gel electrophoresis was performed on these glucagon immunoreactive molecules. The 3H radioactivity and the glucagon immunoreactivity of the smaller molecule were found to co-migrate electrophoretically with crystalline porcine glucagon and monodesamidoglucagon. With electrophoresis at high pH the electrophoretic mobility of the LGI molecule proved to be lower than that of glucagon. Partial tryptic degradation of the human LGI molecule yields 3H-tryptophan labeled products having charge and immunologic characteristics indistinguishable from porcine glucagon and monodesamidoglucagon. Although further investigation is indicatend may thus serve as a precursor or an intermediate in human glucagon biosynthesis.
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PMID:Glucagon biosynthesis in human pancreatic islets: preliminary evidence for a biosynthetic intermediate. 109 15

To selectively isolate hepatocytes from the periportal (PP) and perivenous (PV) regions of rat liver acinus, we compared two different perfusion methods with collagenase: the bidirectional perfusion method (2-P) and the one way perfusion method (1-P). We determined the optimal conditions for each method on the basis of the zonal selectivity of isolated hepatocytes with a hematoxylin-eosin stained liver specimen. By both methods, hepatocytes were selectively isolated from the PP and PV regions. Comparing cell yield and cell viability after the two perfusion methods, 1-P was found to be better than 2-P. Density gradient centrifugation with Percoll was found to be an effective procedure for removing the damaged hepatocytes. We concluded that 1-P could isolate viable PP and PV hepatocytes with a normal glucagon-cyclic AMP response and ultrafine structure in high yield from rat liver.
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PMID:[Comparison of bidirectional collagenase perfusion with one way perfusion in the isolation of periportal or perivenous hepatocytes in rats]. 131 35


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