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Query: UMLS:C0403608 (ureter)
 9,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatocytes were isolated from rats following bilateral nephrectomy, ureter ligation or sham operation under sodium pentobarbital (Nembutal) anesthesia to investigate the potential role of energy charge and redox state for the gluconeogenetic ability of liver cells. Ketogenesis from l-serine, sodium pyruvate or dihydroxyacetone was significantly higher in hepatocytes of acutely uremic rats indicating higher concentration of reducing equivalents in the mitochondria. During incubation, the mitochondrial redox state characterized by beta-hydroxybutyrate/acetoacetate ratio moved into direction of reduction in all experimental groups, whereas cytosolic redox state characterized by lactate/pyruvate ratio shifted to the oxidative state indicating lack of cytosolic reducing equivalents. Hepatocyte ATP and oxoglutarate production of ureter-ligated rats were significantly higher compared with binephrectomized or sham-operated animals independent of the substrates used. Simultaneously, energy charge showed values higher than 0.85 only in hepatocytes of ureter-ligated animals indicating high energy supply for energy requiring processes. We conclude that hepatic gluconeogenesis and ketogenesis of acutely uremic rats are limited by a lack of cytosolic reducing equivalents independent of cell energy supply.
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PMID:Role of energy charge and redox state for hepatocyte gluconeogenesis of acutely uremic rats. 400 Mar 49

Hepatocytes isolated from the livers of starved, sham-operated, bilaterally nephrectomised and ureter-ligated rats as well as rats with ischaemic acute renal failure were used for a comparative study of the effects of different hormones on gluconeogenesis. In all tested groups dibutyryl-3':5'-adenosine monophosphate inhibits glucose synthesis from pyruvate whereas this process is not affected by glucagon and only slightly activated by adrenalin. In contrast, gluconeogenesis from dihydroxyacetone was stimulated by all three hormones at the expense of the conversion of dihydroxyacetone to lactate. In the presence of l-serine adrenalin, glucagon and dibutyryl cAMP also stimulate glucose synthesis, which is more marked in bilaterally nephrectomised and ureter-ligated animals. In half of the experiments with bilaterally nephrectomised rats (group BN 2), lack of sensitivity of hepatocytes to all tested hormones on gluconeogenesis from serine or dihydroxyacetone was observed. The beta-adrenergic antagonist propranolol reduced the stimulatory effect of adrenalin on glucose synthesis from serine and abolished the influence of catecholamines in the presence of dihydroxyacetone and pyruvate. This suggests that both alpha- and beta-receptors are involved in the activation of hepatic gluconeogenesis. Insulin and parathyroid hormone did not change the rate of glucose synthesis in any of the experimental groups.
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PMID:Effect of hormones on hepatocyte gluconeogenesis in different models of acute uraemia. 629 38

Hepatocytes isolated from livers of rats with various models of acute uremia (binephrectomy, ureter ligation, uranyl nitrate-induced, or ischemic ARF) were incubated with glucagon, adrenalin, or cyclic AMP using serine as a substrate. A marked increase in glucose production was observed in the hepatocytes of uranyl nitrate-treated, binephrectomized, and ureter-ligated rats compared to starved controls or sham-operated animals. This effect was strengthened in the presence of glucagon, adrenaline, or cyclic AMP. In liver cells of binephrectomized and ureter-ligated animals, the production of acetoacetate and beta-hydroxybutyrate was significantly higher than in controls and sham-operated rats. Oxoglutarate and ATP production was only enhanced after ureter ligation. The correlation between glucose concentration and the cytosolic redox state was different in control and sham-operated rats than in either uremic group. This study confirms earlier investigations of a key role of serine in carbohydrate metabolism in acutely uremic rats.
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PMID:Effect of serine on gluconeogenic ability of hepatocytes in acute uremia. 633 Apr 26

Liver cells were prepared from untreated controls, rats with various models of acute uraemia (uranyl nitrate-treated, bilaterally nephrectomised and ureter-ligated rats, rats with acute ischaemic renal failure) and sham-operated animals. Hepatocyte glucose output, pyruvate utilisation and lactate production were determined in the presence of Krebs-Ringer bicarbonate buffer with different pH values (7.1, 7.4, 7.6) using pyruvate, dihydroxyacetone, serine and fructose as substrates. In the presence of pyruvate and dihydroxyacetone a significant increase of glucose production in hepatocytes from bilaterally nephrectomised and ureter-ligated rats was observed. However, pyruvate-generated glucose production in the hepatocytes of uranyl nitrate-treated animals was unchanged, while a diminished glucose output was seen in the presence of dihydroxyacetone. A marked increase in glucose and lactate production in the presence of serine was observed in the hepatocytes of uranyl nitrate-treated, ureter-ligated and binephrectomised rats. However, lactate production from dihydroxyacetone in the liver cells of uranyl nitrate-treated animals was inhibited. In contrast to other types of uraemia, in acute ischaemic renal failure there is significantly lower hepatocyte glucose production using pyruvate as a substrate, but unchanged glucose generation from dihydroxyacetone or serine.
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PMID:The gluconeogenetic ability of hepatocytes in various types of acute uraemia. 681 Jan 92

Disturbances of carbohydrate metabolism during acute uraemia are characterized by the degradation of liver and muscle glycogen with a simultaneous activation of hepatic gluconeogenesis. After binephrectomy, the substitution of essential amino acids and keto analogues stimulate liver, but not skeletal muscle glycogen synthesis. Serine proves to be an optimal substrate for liver gluconeogenesis and muscle glycogen generation under acute uraemic conditions. Propranolol does not influence glycogenolysis of skeletal muscle in acutely uraemic rats. During starvation, acute uraemia leads to an increase of total carbohydrate content as well as of glycogen and glucose concentrations in heart muscle Alterations in carbohydrate contents are not observed in the kidney after ureter ligation. Enhanced glycogenolysis of skeletal muscle and liver during acute uraemia may be due to activation of phosphorylase kinase caused by the increased serum concentrations of various hormones (glucagon, catecholamines, parathormone) as well as free proteolytic activity, an increase of intracellular Ca2+-concentration and finally by alterations in the structure of contractile proteins.
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PMID:Carbohydrate metabolism and uraemia-mechanisms for glycogenolysis and gluconeogenesis. 745 93

1 This study was designed to investigate the effect of 5-hydroxytryptamine (5-HT) and to characterize the 5-HT receptors involved in 5-HT responses in the pig intravesical ureter. 2 5-HT (0.01-10 microM) concentration-dependently increased the tone of intravesical ureteral strips, whereas the increases in phasic contractions were concentration-independent. The 5-HT(2) receptor agonist alpha-methyl 5-HT, mimicked the effect on tone whereas weak or no response was obtained with 5-CT, 8-OH-DPAT, m-chlorophenylbiguanide and RS 67333, 5-HT(1), 5-HT(1A), 5-HT(3) and 5-HT(4) receptor agonists, respectively. 5-HT did not induce relaxation of U46619-contracted ureteral preparations. Pargyline (100 microM), a monoaminooxidase A/B activity inhibitor, produced leftward displacements of the concentration-response curves for 5-HT. 3 5-HT-induced tone was reduced by the 5-HT(2) and 5-HT(2A) receptor antagonists ritanserine (0.1 microM) and spiperone (0.2 microM), respectively. However, 5-HT contraction was not antagonized by cyanopindolol (2 microM), SDZ-SER 082 (1 microM), Y-25130 (1 microM) and GR 113808 (0.1 microM), which are respectively, 5-HT(1A/1B), 5-HT(2B/2C), 5-HT(3), and 5-HT(4) selective receptor antagonists. 4 Removal of the urothelium did not modify 5-HT-induced contractions. Blockade of neuronal voltage-activated sodium channels, alpha-adrenergic receptors and adrenergic neurotransmission with tetrodotoxin (1 microM), phentolamine (0.3 microM) and guanethidine (10 microM), respectively, reduced the contractions to 5-HT. However, physostigmine (1 microM), atropine (0.1 microM) and suramin (30 microM), inhibitors of cholinesterase activity, muscarinic- and purinergic P(2)-receptors, respectively, failed to modify the contractions to 5-HT. 5 These results suggest that 5-HT increases the tone of the pig intravesical ureter through 5-HT(2A) receptors located at the smooth muscle. Part of the 5-HT contraction is indirectly mediated via noradrenaline release from sympathetic nerves.
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PMID:Characterization of the 5-hydroxytryptamine receptors mediating contraction in the pig isolated intravesical ureter. 1252 83