Search results for "PHOSPHATE"
showing 10 items of 1874 documents
Effects of insulin-like growth factor I on the rates of glucose transport and utilization in rat skeletal muscle in vitro.
1992
1. The effects of insulin-like growth factor I (IGF-I) on the rates of glucose transport and utilization and its interaction with insulin were investigated in rat soleus muscle in vitro. IGF-I increased the rates of glucose transport, lactate formation, glycogen synthesis and the flux of glucose to hexose monophosphate, but it had no effect on the rate of glucose oxidation or glycogenolysis. 2. In the absence of insulin, low levels of IGF-I (0-30 ng/ml) increased the rate of glycolysis and the content of fructose 2,6-bisphosphate, but the content of glucose 6-phosphate remained unaltered; at higher levels of IGF-I (300-3000 ng/ml) the rate of glycolysis and the content of fructose 2,6-bisph…
Pre- and postjunctional effects of diadenosine polyphosphates in the guinea-pig vas deferens.
1995
Abstract The pre- and postjunctional activities of a number of diadenosine polyphosphates were examined in the guinea-pig isolated vas deferens at the level of the membrane-potential, using a modified sucrose-gap technique. P1,P3-Di(adenosine 5′)triphosphate (Ap3A), P1,P4-di(adenosine 5′)tetraphosphate (Ap4A) and P1,P5-di(adenosine 5′)pentaphosphate (Ap5 A) all caused concentration-dependent depolarization of the smooth muscle membrane. The potency order was: Ap5A > Ap4A. Ap3A. P1, P2-Di(adenosine 5′)pyrophosphate (Ap2A) did not evoke depolarization even at the highest concentration tested (1 mM). All the dinucleotides caused a reduction in the amplitude of evoked excitatory junction…
Protection effect of endurance training against reoxygenation-induced injuries in rat heart
1990
Endurance training by swimming (219-229 h) resulted in a significant protection against hypoxia/reoxygenation-induced injuries in Langendorff-perfused rat hearts. The protection was manifested as improved flow characteristics and a smaller release of creatine kinase into the perfusate. The concentration of thiobarbituric acid reactive substances (TBARS) was lower in the trained than in the respective control hearts. The trained hearts also showed a lower reoxygenation-induced increase in TBARS. The myocardium of the right ventricle and that of the left subepimyocardium were the most affected by reoxygenation. The swimming program induced a decrease in the activities of catalase and glutath…
Exhaustive physical exercise and acid hydrolase activity in mouse skeletal muscle
1978
Adult, untrained NMRI mice were exhausted on a motor-driven treadmill by an intermittent-type running programme. Serial cryostate sections for the staining of NADH-tetrazolium reductase, beta-glucuronidase, beta-N-acetylglucosaminidase, and beta-glycerophosphatase activities and for making hematoxylin-eosin staining were cut from m. quadriceps femoris 1, 2, 3, 5, 7, and 15 days after physical exhaustion. A strong increase in the activities of beta-glucuronidase and beta-N-acetylglucosaminidase was observed 7 days after exhaustion and the activity changes, which were similar for the both glycosidases, were more prominent in the highly oxidative red compared to less oxidative white fibres. Ac…
Influence of therapeutic and toxic doses of neuroleptics and antidepressants on energy metabolism of the isolated perfused rat brain.
1973
The isolated perfused rat brain was used for a comparative study of the effects of promazine, imipramine, monodesmethyl promazine and desipramine on cerebral energy metabolism. After perfusion for 30 min or 1 h the brain levels of the following substrates and metabolites were estimated: P-creatine, creatine, ATP, ADP, AMP, glycogen, glucose, glucose-6-P, fructose diphosphate, dihydroxyacetone-P, pyruvate, lactate, α-ketoglutarate, and ammonia. Drug concentrations of 5·10−6 M and 10−5 M in the perfusion medium caused a significant decrease of glucose-6-P alone. When the drug concentration was raised to a toxic range (10−4 M), reflected in the EEG by the pattern of secondary discharges, an ac…
Effect of acidosis on lipid peroxidation in brain slices.
1991
Acidification of the incubation medium markedly increased lipid peroxidation of cortical brain slices. Lactic acidosis caused a more extensive lipid peroxidation than did phosphoric acidosis (+35% at pH 6 and +81% at pH 5), probably due to the rapid diffusion of the protonated form of lactic acid across cell membranes. These results support the hypothesis that free radical mechanisms may be involved in the cytotoxicity of acidosis.
A new method to measure cardiac inositol levels in intact animals.
1996
Inositol levels have been studied in cellular cultures and recently by perfusion of isolated hearts. The study was aimed to assess inositol turnover in rabbit hearts from intact animals. Thirty rabbits were injected i.v. three times (every 12 hr) with 25 microCi/kg of myo-3H-inositol. The rabbits 12 hr after the last injection were killed and the hearts perfused according to Langerdorff technique. Systolic and diastolic ventricular pressures (SVP, DVP), dp/dt, and coronary flow (CFl) were measured. The hearts (n = 14) were perfused under aerobic conditions and 16 hearts under ischemic conditions for 30 min. In addition, 5 hearts were perfused under aerobic conditions for 10 min, and 6 heart…
The Oxidative Stress Concept of Nitrate Tolerance and the Antioxidant Properties of Hydralazine
2005
The hemodynamic and anti-ischemic effects of nitroglycerin (NTG) are rapidly blunted as a result of the development of nitrate tolerance. With initiation of NTG therapy, it is possible to detect neurohormonal activation and intravascular volume expansion. These so-called pseudotolerance mechanisms may compromise the vasodilatory effects of NTG. Long-term nitrate treatment also is associated with decreased vascular responsiveness caused by changes in intrinsic mechanisms of the tolerant vasculature itself. According to the oxidative stress concept, increased vascular superoxide (O 2 − ) production and an increased sensitivity to vasoconstrictors secondary to activation of protein kinase C co…
Effects of glucocorticoid excess on the sensitivity of glucose transport and metabolism to insulin in rat skeletal muscle.
1997
This study examines the mechanisms of glucocorticoid-induced insulin resistance in rat soleus muscle. Glucocorticoid excess was induced by administration of dexamethasone to rats for 5 days. Dexamethasone decreased the sensitivity of 3-O-methylglucose transport, 2-deoxyglucose phosphorylation, glycogen synthesis and glucose oxidation to insulin. The total content of GLUT4 glucose transporters was not decreased by dexamethasone; however, the increase in these transporters in the plasma membrane in response to insulin (100 m-units/litre) was lessened. In contrast, the sensitivity of lactate formation to insulin was normal. The content of 2-deoxyglucose in the dexamethasone-treated muscle was …
Cannabinoid type 1 receptor blockade promotes mitochondrial biogenesis through endothelial nitric oxide synthase expression in white adipocytes
2008
OBJECTIVE—Cannabinoid type 1 (CB1) receptor blockade decreases body weight and adiposity in obese subjects; however, the underlying mechanism is not yet fully understood. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) induces mitochondrial biogenesis and function in adipocytes. This study was undertaken to test whether CB1 receptor blockade increases the espression of eNOS and mitochondrial biogenesis in white adipocytes. RESEARCH DESIGN AND METHODS—We examined the effects on eNOS and mitochondrial biogenesis of selective pharmacological blockade of CB1 receptors by SR141716 (rimonabant) in mouse primary white adipocytes. We also examined eNOS expression and mitochondrial biog…