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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possibility that hormones control hepatic gluconeogenesis via the regulation of the rate of mitochondrial pyruvate carboxylation was investigated with the use of suspensions of liver cells isolated from fasted rats. The mitochondria prepared from liver cells were judged in good condition as they exhibited satisfactory phosphorus-oxygen and respiratory control ratios and transported Ca2+ and K+ ions in an energy-dependent manner. Addition of glucagon, epinephrine, or cyclic adenosine 3':5'-monophosphate to liver cells caused a 50 to 80% increase in the rate of glucose synthesis from lactate. When mitochondria were isolated from the cells after treatment with these agonists, they displayed 2- to 3-fold increases in the rate of pyruvate carboxylation, pyruvate decarboxylation, and pyruvate uptake. These mitochondrial changes are similar to those obtained in hepatic mitochondria prepared from intact, hormone-treated rats. The mitochondrial responses were specific for agents that stimulated gluconeogenesis; no response occurred with 5'-AMP or cyclic adenosine 2':3'-monophosphate. In the cell suspensions, the dose response curves for the activation of mitochondrial pyruvate metabolism and for increased glucose synthesis from L-lactate were coincident with four different agonists. The mitochondrial changes resulting from stimulation with glucagon developed in 1 to 2 min after the rise in cyclic adenosine 3':5'-monophosphate and occurred at least as early as the increase in the rate of gluconeogenesis. When the intracellular level of cyclic adenosine 3':5'-monophosphate returned to basal values, the rates of mitochondrial pyruvate carboxylation and glucose synthesis also declined to control levels. It is concluded that the rate of mitochondrial pyruvate metabolisms can be increased by hormones and cyclic nucleotides and that control of mitochondrial pyruvate carboxylation is an important regulatory site of hepatic gluconeogenesis.
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PMID:The hormonal control of gluconeogenesis by regulation of mitochondrial pyruvate carboxylation in isolated rat liver cells. 16 52

New concepts concerning the pathogenesis and therapy of diabetic ketoacidosis are reviewed. The regulation of ketogenesis by intrahepatic enzymic processes and the roles of insulin deficiency or glucagon or other counterregulatory hormone excess are summarized. Major emphasis is placed on an analysis of the use of low-dose insulin regimens for the treatment of ketoacidosis. Most patients with diabetic ketoacidosis will respond to low-dose, hourly, intravenous or intramuscular regular insulin. Low doses of insulin are as effective as high doses and have fewer associated complications of hypoglycemia and hypokalemia. Phosphorus deficiency is common in diabetic ketoacidosis and hypophosphatemia usually becomes manifest within 4 to 12 h of institution of therapy. Phosphorus supplementation is now generally recommended to replete erythrocyte 2,3-diphosphoglycerate and improve oxygen delivery to tissues. Coexistent and biochemically significant lactic acidosis is a relatively infrequent complication of diabetic ketoacidosis and when present is usually due to underlying disorders associated with poor tissue perfusion.
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PMID:Diabetic ketoacidosis: new concepts and trends in pathogenesis and treatment. 41 52

To elucidate pathogenetic factors of bone mineral loss in diabetes mellitus, bone mineral content (BMC), glucose and calcium homeostasis were evaluated in a cross-sectionsl study of 215 insulin-treated diabetics. BMC declined 10% during the first 5 years of diabetes. This coincided with cessation of insulin secretion, deterioration of metabolic control and raising urinary calcium excretion rates of calcium and phosphorus. BMC was inversely correlated to fasting blood glucose (P less than 0.02), to glycosuria (P less than 0.02) and to insulin requirement (P less than 0.002), and positively to the glucagon-stimulated serum C-peptide levels (P less than 0.005). Urinary excretion rates of calcium and phosphorus correlated positively with the degree of hyperglycaemia (P less than 0.001) and glycosuria (P less than 0.001). The skeletal calcium loss corresponded to the excess of urinary excretion during the phase of BMC reduction. There was no evidence of secondary hyperparathyroidism. The relationship between bone loss and disturbed glucose homeostasis indicates that diabetic bone loss is secondary to the metabolic abnormalities, possibly acting directly on bone.
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PMID:Bone mineral loss in insulin-treated diabetes mellitus: studies on pathogenesis. 42 86

Pancreatitis was induced in 11 miniature pigs by infusing a bile salt-trypsin solution into the pancreatic duct. Seven animals served as sham-operated controls. Serum ionized calcium, total calcium, albumin, total protein, inorganic phosphorus, urea nitrogen, magnesium, insulin, glucagon, and hematocrit were determined every six to 12 h over a period of one week in both test and control animals. We observed significant decreases in ionized and total calcium, modest decreases in albumin, and significant increases in the inorganic phosphorus, urea nitrogen, and hematocrit in the pancreatitic pigs. The latter two findings were consistent with early acute hypovolemia. Glucagon and insulin appeared to play no role in the hypocalcemia. Glucagon concentrations increased to the same degree in both test and control animals, probably as a result of the stress of being handled and operated on. The highest concentrations of inorganic phosphorus and the lowest concentrations of both ionized and total calcium were seen 18 h after the induction of pancreatitis in the test animals. These findings suggest that parathyrin (parathormone) was not being secreted in adequate amounts, or that the target organs were unresponsive to parathyrin.
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PMID:Biochemical changes in a porcine model of acute pancreatitis. 65 76

Plasma glucose, insulin, and alpha-cell glucagon profiles were examined in ten adults with uncomplicated primary hyperparathyroidism before and 8-12 week after surgical removal of a single parathyroid adenoma. Treatment restored abnormal serum calcium and phosphorus concentrations to a normal range and reduced serum parathyroid hormone levels from 47 +/- 4 to 16 +/- 4 mu 1 Eq/ml (normal = 0-40). Plasma glucose curves during 100-g oral glucose tolerance, 30 min intravenous glucose (1.5 g/min), or arginine infusions (1.0 g/min) did not differ before and after surgery. However, basal and peak insulin concentrations were higher before treatment during these tests (p less than 0.05). Basal glucagon levels were unaffected by hyperparathyroidism (72 +/- 7 versus 77 +/- 7 pg/ml). Peak 30 min values after arginine provocation were also similar before and after treatment as was maximal suppression of basal glucagon during glucose infusions. Four patients also received 400 g lean beef meals. Glucose and glucagon responses over 240-min periods were nearly identical before and after surgery despite higher insulin levels before treatment. It is concluded that elevated serum parathyroid hormone and plasma insulin concentrations in primary hyperparathyroidism do not relate to abnormalities of plasma alpha-cell glucagon in the basal state or after glucose, arginine, or protein administration.
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PMID:Plasma alpha-cell glucagon in primary hyperparathyroidism. 78 68

To evaluate the effect of physiologic hyperglucagonemia on nitrogen and glucose metabolism and on urinary electrolyte excretion, pancreatic glucagon was administered as a continuous 3-day infusion to three adult-onset non-insulin-dependent diabetics and two insulin-treated juvenile diabetics while on a constant dietary intake. The glucagon infusion resulted in increases in plasma glucagon which were 4-6 fold greater than control values. Despite prolonged hyperglucagonemia, urinary glucose excretion was unchanged. Similarly, urinary urea nitrogen and total nitrogen excretion were not altered by glucagon administration. Urinary sodium tended to rise, albeit not significantly (p less than .01), on the first infusion day, but later declined to control values despite increasing plasma glucagon concentrations. Urinary chloride, potassium, calcium, phosphorus excretion remained unchanged. We conclude that continuous physiologic increments in plasma glucagon do not enhance glycosuria or increase protein catabolism and ureagenesis in diabetes when insulin is available. The augmented protein catabolism and glucogenesis that accompany diabetic ketoacidosis cannot be explained primarily on the basis of hyperglucagonemia.
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PMID:Influence of physiologic hyperglucagonemia on urinary glucose, nitrogen, and electrolyte excretion in diabetes. 83 43

Variables of calcium metabolism were measured in 11 patients with clearly documented acute pancreatitis. Total and ionized calcium levels were either low or in the low-normal range as were phosphorus and total magnesium levels. Parathyroid hormone levels were high, and there was a significant inverse correlation with ionized calcium. Gastrin levels were normal, calcitonin values were uniformly below the detection limit of the assay, and pancreatic glucagon levels were elevated. The hypocalcemia of acute pancreatitis was probably not caused by abnormalities of glucagon, calcitonin, or gastrin secretion. Furthermore, parathyroid hormone secretion was apparently not impaired. Hypomagnesemia possibly played a minor role. This study suggests that the hypocalcemia of acute pancreatitis is secondary to extraskeletal calcium sequestration or an as yet unidentified defect of bone metabolism, or both.
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PMID:The hypocalcemia of acute pancreatitis. 114 52

The renal effect of cyclic somatostatin was studied on healthy subjects. The somatostatin was used at therapeutical dose in intravenous infusion. Somatostatin decreases the renal plasma flow, glomerular filtration rate, osmotic and free water clearances, sodium and potassium excretion and the tubular reabsorption of phosphorus while urinary osmolality increases. Under somatostatin infusion the urinary excretion of catecholamines, PGE2, PGF2 alfa and the plasma renin activity and the plasma concentration of glucagon and growth hormone decrease. The antidiuretic activity of somatostatin is due to a) a direct haemodinamic effect, b) an influence on the renal tubular transport as well and also c) because of change the water handling in the collecting ducts.
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PMID:[Effect of somatostatin on kidney function]. 168 89

In a double-blind placebo-controlled study the effect of glucagon on gastric emptying, as well as on serum concentrations of gastrin, insulin, glucose, calcium, and phosphorus after ingestion of a mixed solid-liquid meal was examined in nine normal males. An i.v. bolus of 0.5 mg of crystalline glucagon was followed by 1.5 mg infused at a constant rate over 90 minutes. The gastric emptying of a radiolabelled meal was measured with the use of a gamma camera. Glucagon evoked a marked delay in gastric emptying in all patients studied--the emptying index, Ix: 2.065 +/- 0.211 min-1 after placebo vs 0.358 +/- 0.090 min-1 after glucagon, p less than 0.01. The postprandial gastrin release was suppressed during the first 60 minutes of glucagon infusion and occurrence of the postprandial increment in the serum gastrin concentration was delayed. The integrated gastrin response did not, however, significantly change: the area under the gastrin curve, AUC0-90, 8733 +/- 1502 min.ng.l-1 after placebo vs 7434 +/- 1372 min.ng.l-1 after glucagon. A promotion of insulin release by glucagon was reflected by a significant increase in the area under the insulin curve, AUC0-90: 1842 +/- 153 min.mU.l-1 after placebo vs 3388 +/- 567 min.mU.l-1 after glucagon, p less than 0.02. Moreover, a sooner and significantly higher increase of the serum glucose level was observed during glucagon infusion when compared to the placebo situation. Glucagon did not significantly change the serum calcium level, whereas the serum phosphorus concentration was markedly lowered throughout glucagon infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of glucagon on gastric emptying and on postprandial gastrin and insulin release in man. 248 72

Phosphorus is the sixth most abundant element in the body after oxygen, hydrogen, carbon, nitrogen, and calcium. It comprises about 1% of the total body weight of humans. Eighty-five percent of it is stored in the bone in the form of hydroxyapatite crystal; 14% is in the soft tissues in the form of energy-storing bonds with nucleotides (ATP, GTP), nucleic acids in chromosomes and ribosomes, 2,3-DPG in the red blood cells, and phospholipids in the cells' membranes. Less than 1% is in the extracellular fluids. Phosphate balance is maintained by multiple systems. The gut is responsible for the absorption of two thirds of the 4-30 mg/kg/day of phosphate intake. Absorption sites are all along the gut; in humans the most active site is the jejunum. The kidney filters 90% of the plasma phosphate and reabsorbs it in the tubuli. In states of hypophosphatemia the kidney can reabsorb the filtered phosphates very efficiently, reducing the amount excreted in the urine virtually to zero. The healthy kidney can excrete high loads of phosphate and rid the body of phosphate overload. Through the vitamin D-PTH axis the endocrine system regulates the phosphate balance by influencing the kidney, gut, and bone. Other hormones, including thyroid, insulin, glucagon, glucocorticosteroid, and thyrocalcitonin, play a lesser role in regulation of phosphate metabolism. Because of the complex control of phosphate homeostasis, various clinical conditions may lead to hypophosphatemia. These include nutritional repletion, gastrointestinal malabsorption, use of phosphate binders, starvation, diabetes mellitus, and increased urinary losses due to tubular dysfunction. The clinical picture of phosphate depletion is manifested in different organs and is due mainly to the fall in intracellular levels of ATP and decreased availability of oxygen to the tissues, secondary to 2,3-DPG depletion. The various manifestations of phosphate depletion are listed in Table 2. The treatment of hypophosphatemia consists of administering enteral or parenteral phosphate salts. An important aspect of dealing with the potentially serious effects of phosphate depletion is to prevent the depletion from happening in the first place. Hyperphosphatemia can occur in renal failure, hemolysis, tumor lysis syndrome, and rhabdomyolysis. The treatment of hyperphosphatemia usually consists of fluid administration (in the absence of kidney failure). In chronic hyperphosphatemia, phosphate binders such as aluminum and magnesium salts can reduce the phosphate load. The use of these phosphate binders is limited by their potential side effects.
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PMID:Consequences of phosphate imbalance. 306 Jan 61


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