Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:034761 (insulin)
 211,843 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Daily evaluations of 8 newly detected ketoacidotic diabetics showed the Bohr-effect of haemoglobin to be decreased by 50% while erythrocyte 2,3-DPG was decreased below 10 mumoles/g Hb. 2,3-DPG correlated strongly with pH during acidosis and with plasma inorganic phosphate (Pi) subsequently to the first insulin administration. Oxygen affinity of haemoglobin, measured as P50 act pH, was unchanged in ketoacidosis compared to the time, however, P50 act pH fell striking (p less than 0.001) and remained decreased up to 7 days depending upon the resynthesis of 2,3-DPG in relation to Pi. The Hill-coefeficient in reflecting the slope of the oxygen dissociation curve was diminished in ketoacidosis (p less than 0.005), and decreased further after pH-normalization (p less than 0.005). There was a close association of n with 2,3-DPG (p less than 0.001) and additionally with Pi at 2,3-DPG-levels below 10 mumoles/g Hb. Based on these findings a decreased erythrocyte oxygen release of one fifth during acidosis and more than one third after pH-correction can be hypothesised. In view of the intimate relation of Pi to the oxygen transport system it is suggesed that treatment of ketoacidosis should include Pi-sugstitution.
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PMID:The oxygen transport system of red blood cells during diabetic ketoacidosis and recovery. 0 19

The isolated perfused working rat heart preparation has been used to study the effects of respiratory acidosis on myocardial metabolism and contractilly. Hearts were perfused with 5 mM glucose and 10(-2) U/ml of insulin in order to enhance metabolsim of glucose relative to that of fatty acids. After perfusion with Krebs bicarbonate medium at pH 6.6, hearts rapidly ceased performing external work and peak left ventricular pressure fell by 75% after 5 minutes. Oxygen consumption, rate of ATP generation and overall glycolytic flux also declined rapidly. After about 2 minutes of perfusion, the fall of glycolytic flux showed a partial reversal, which was largely accounted for by increased lactate production, so that glucose oxidation decreased further. The reversal of glycoltic flux could be accounted for by partial release of H+ inhibition of phospho-fructokinase by increased tissue levels of adenosine 5'-diphosphate (ADP), adenosine monophosphate (AMP) and P1 and decreased levels of adenosine triphosphate (ATP) and creatine phosphate. The increased proportion of glucose uptake converted to lactate together with an increase of the tissue lactate/pyruvate ratio could be accounted for by inhibition of the malate-aspartate cycle combined with tissue hypoxia. Lactate accumulated in the tissue as a result of a decreased permeability of the plasma membrane to lactate. Decreased oxygen delivery to the myocardium was caused by secondary constriction of the coronary vessels. In further experiments, the coronary flow was regulated by an external pump which delivered fluid at a controlled rate into the aortic cannula above the coronary arteries, and the degree of tissue hypoxia was monitored by measuring changes of pyridine nucleotide reduction state by surface fluorescence techniques. The effects of acidosis uncomplicated by possible hypoxia were compared directly with those produced by ischemic hypoxia. The effects of acidosis under these conditions were similar to those described above, and to those produced by ischemia. From these and other data it is concluded that the effects of ischemia are caused by a lowering of the intracellular pH, which decreases the rate of energy production relative to the rate of energy demand. However, it is suggested that the primary cause of the decreased peak systolic pressure with either acidosis or ischemia is not a result of a defect of energy metabolism, but is due to alteration of the calcium cycle of the heart. Possible causes of irreversible heart failure after prolonged ischemia are discussed.
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PMID:Contribution of tissue acidosis to ischemic injury in the perfused rat heart. 0 93

Significant alterations in heart carbohydrate and lipid metabolism are present 48 h after intravenous injection of alloxan (60 mg/kg) in rats. It has been suggested that uncoupling of oxidative phosphorylation occurs in the alloxanized rat heart in vivo, whereas normal oxidative metabolism has been demonstrated in alloxan-diabetic rat hearts perfused in vitro under conditions of adequate oxygen delivery. We examined the hypothesis that high-energy phosphate metabolism might be adversely affected in the alloxan-diabetic rat heart in vivo. Phosphocreatine and ATP were reduced by 58 and 45%, respectively (P is less than 0.001). Also, oxygen-dissociation curves were shifted to the left by 4 mmHg, and the rate of oxygen release from blood was reduced by 21% (P is less than 0.01). Insulin administration normalized heart high-energy phosphate compounds. ATP production was accelerated in diabetic hearts perfused in vitro with a well-oxygenated buffer. These studies support the hypothesis that oxidative ATP production in the alloxan-diabetic rat heart is reduced and suggest that decreased oxygen delivery may have a regulatory role in the oxidative metabolism of the diabetic rat heart.
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PMID:Reduced high-energy phosphate levels in rat hearts. I. Effects of alloxan diabetes. 0 45

Oxyhemoglobin dissociation curves (ODC) from zero to full saturation were developed from tests performed on whole blood from various groups of diabetic and nondiabetic healthy subjects. P50 at in-vivo pH was slightly but significantly lower than normal in ambulatory nonacidotic, uncomplicated juvenile diabetics (26.0 vs. 27.3 mm. Hg, P less than 0.001), despite increased red cell 2,3-diphosphoglycerate (2,3-DPG) concentrations in diabetic erythrocytes (15.0 vs. 13.7 mumole/gm. Hb, P less than 0.001). This combination of changes is in keeping with the presence of increased proportions of hemoglobin AIc in insulin-treated diabetics. The position of the ODC was positively correlated with the 2,3-DPG concentration (P less than 0.01), which varied in response to fluctuations in plasma concentration of inorganic phosphate (Pi) (P less than 0.001). Optimal metabolic control may lead to a normalization of the ODC in association with increased concentrations of red cell 2,3-DPG and P. When the diabetes was uncontrolled, the ODC was usually unchanged during the acidotic phase because the lowered pH balanced the effect of diminished 2,3-DPG concentration on the ODC. After correction of acidosis, the disproportion between erythrocyte 2,3-DPG and pH became quite prominent, accompanied by a corresponding fall in P50 (21.0 vs. 26.1 mm. Hg, P less than 0.001). Following ketoacidosis, with a persistently lowered Pi, it may take up to one week for 2,3-DPG to return to an approximately normal level, and the P50 will be impaired for the same period. A diphosphonate (EHDP) known to enhance tubular phosphate reabsorption in man was given to nonacidotic insulin-treated diabetic and healthy volunteers for 28 days. It caused a significant increase in mean Pi and P50 in both healthy and diabetic subjects (r = 0.58, P less than 0.01). When a dietary supplement of dibasic calcium phosphate was given to diabetic subjects for 28 days, a significant increase in P50 also occurred (25.2 vs. 27.2 mm. Hg, P less than 0.001). It is recommended that the diabetes diet be supplemented by dibasic calcium phosphate to prevent the inhibitory effect of a low concentration of Pi on red cell oxygen delivery.
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PMID:Oxygen transport impairment in diabetes. 0 22

In vitro addition of rat insulin (200, 400 or 800 muU/ml) to collagenase-isolated pancreatic islets of adult rats diminished glucose (3 mg/ml)-induced insulin release which was correlated with a decrease of the ratio of total NADPH/NADP and inhibition of glucose oxidation via the pentose phosphate shunt (PPS). NADH and NAD levels were not affected. It is suggested that exogenous insulin diminishes the islet total NADPH/NADP ratio by a direct or indirect decrease in PPS activity. However, it is also conceivable that insulin decreases this ratio through another mechanism than PPS. It is possible that inhibition of insulin secretion by exogenous insulin is at least in part due to the decrease of the NADPH/NADP ratio.
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PMID:Pyridine nucleotides in pancreatic islets during inhibition of insulin release by exogenous insulin. 1 90

Reduced nicotinamide adenine dinucleotide phosphate (NADPH), which stimulated the release of insulin from toadfish islet cells and from isolated secretion granules, was taken up by the membranes prepare from these secretion granules. Oxidized nicotinamide adenine dinucleotide phosphate, which did not release insulin from the granules, was taken up to a much lesser extent. The uptake of NADPH by the granule membranes was time dependent, reaching equilibrium in about 30 min. The maximum amount of NADPH taken up was 0.6 nmol/mg membrane protein and the concentration of NADPH needed to obtain maximum uptake was 6.5 x 10(-4)m, which was approximately the same concentration of NADPH needed to produce maximum release of insulin from the secretion granules.
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PMID:Uptake of NADPH by islet secretion granule membranes. 1 21

The relation between serum and red blood cell (RBC) inorganic phosphate levels, RBC 2,3-diphosphoglycerate (2,3-DPG) levels, RBC nucleotide phosphate (Pn), and RBC total phosphate (Pt) levels were studied during the early phases of treatment and recovery from diabetic ketoacidosis (DKA). A steady drop in serum inorganic phosphate was found during the first 24 hours of insulin treatment and was most profound at 24 hours. No statistically significant changes (P less than 0.05) were found in red cell inorganic phosphate or nucleotide phosphate levels during the 24-hour study period. The levels of total red cell phosphate were lower in this group of patients than in nonacidotic diabetic subjects and decreased slightly after 24 hours of treatment. The red cell 2,3-DPG levels were low at the initiation of therapy and remained low during the 24-hour study period. Glucose, bicarbonate, lactate, and ketone levels fell in linear patterns with treatment. In view of the current evidence for the effects of low 2,3-DPG on oxygen delivery and the relation of low serum phosphate levels to RBC glycolysis and 2,3-DPG formation, this study reemphasizes the need for phosphate replacement during the early phases of treatment of DKA.
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PMID:2,3-diphosphoglycerate, nucleotide phosophate, and organic and inorganic phosphate levels during the early phases of diabetic ketoacidosis. 1 18

Inhibition of glucose-stimulated insulin release by exogenous insulin has been demonstrated in pancreatic islets to be associated with a decrease of the NADPH/NADP ratio and the pentose-phosphate cycle activity. Batches of five islets were incubated for 15 and 90 minutes in 1 ml. of KRB buffer with 2 per cent albumin containing 3 mg./ml. glucose and 0, 200, 400, or 800 microU./ml. of rat insulin, and the glucose-6-phosphate (G6P) and 6-phosphogluconate (6PG) contents were determined by enzymatic cycling. In response to a rise in the concentration of insulin, the 6PG/G6P ratio decreased. A close relationship was observed between this decrease of 6PG/G6P ratio and the net insulin release, the absolute rate of glucose oxidation via the pentose phosphate cycle, and the NADPH/NADP ratios measured under similar conditions. The results suggest that exogenous insulin, directly or indirectly, regulates the pentose cycle activity in the pancreatic islets at the G6P dehydrogenase step.
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PMID:6-Phosphogluconate/glucose-6-phosphate ratio in rat pancreatic islets during inhibition of insulin release by exogenous insulin. 1 30

The effect of oral disodium ethane-1-hydroxy-1,1-diphosphonate, EHDP (20 mg kg-1 day-1) and placebo given for 28 days on plasma inorganic phosphate (Pi) red cell 2,3-diphosphoglycerate and oxygen affinity of hemoglobin was evaluated in 14 insulin-treated diabetics and 5 healthy volunteers. EHDP significantly increased mean Pi (diabetics: 1.18 to 1.67 mmol/l, p less than 0.01, controls: 1.03 to 1.71 mmol/l, p less than 0.02) and P50 at in vivo pH of the oxyhemoglobin dissociation curve (diabetics: 25.4 to 26.6 mmHg, p less than 0.02; controls: 26.3 to 28.9 mmHg, p less than 0.02). Pi and P50 were correlated in both diabetics and in controls (p less than 0.05). 2,3-DPG increased when the diabetics were on EHDP (p less than 0.005). The study emphasizes the importance of Pi on red cell function and indicates that an elevation of Pi tends to counteract the defect in oxygen release capacity of the red cells in diabetic subjects.
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PMID:Effect of the diphosphonate EHDP on plasma inorganic phosphate and hemoglobin oxygen affinity of diabetic and healthy subjects. 1 49

Tyrosine adminotransferase (EC 2.6.1.5) has been found to be phosphorylated in intact rat hepatoma cells in culture. Incorporation of [32p]i into the enzyme is rapid and is exclusively found as phosphoserine. Cycloheximide treatment reduced phosphorylation of the aminotransferase only slightly and in the presence of three different inducers of this enzyme, dexamethasone, insulin, and dibutyryl cyclic AMP, [32P]I incorporation was increased. It is concluded that [32p]i incorporation into this enzyme probably reflects turnover of phosphate groups associated with pre-existing enzyme molecules catalyzed by a cyclic AMP-independent protein kinase.
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PMID:Relationship between phosphorylation of tyrosine aminotransferase and regulation of its synthesis by cyclic AMP and hormones. 2 2


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