Elevated Phosphate Concentrations Research Articles

31P nuclear magnetic resonance evidence of abnormal skeletal muscle metabolism in patients with congestive heart failure

In patients with congestive heart failure (CHF), exercise limitation correlates poorly with central hemodynamic abnormalities, suggesting that additional abnormalities in skeletal muscle blood flow or metabolism play an important pathophysiologic role. Therefore, muscle metabolism was examined by 31P nuclear magnetic resonance (NMR) at rest and during repetitive bulb squeeze exercise in 11 patients with New York Heart Association class II to IV CHF and 7 age-matched control subjects. Serial spectra were obtained at rest, at 2 levels of exercise and during recovery. At rest, the only abnormal finding was an elevated inorganic phosphate (P i) concentration (5.0 ± 1.5 vs 3.6 ± 0.4 m M, p < 0.01). At the lower exercise level, phosphocreatine (PCr) utilization, which was followed as the ratio of [PCr] ([PCr] + [P i]) , was greater (0.36 ± 0.16 vs 0.53 ± 0.10, p < 0.02), and pH fell more rapidly and to a lower value (6.38 ± 0.25 vs 6.85 ± 0.17, p < 0.001). At the higher level of exercise, the patients could not work effectively and the group differences narrowed. Compared with control subjects, acidification was disproportionately greater in relation to PCr depletion in patients, further suggesting excessive dependence on glycolytic metabolism. The P i peak was prominently double in 5 patients, indicating presence of a population of muscle fibers undergoing unusually active glycolysis. PCr resynthesis, a reflection of oxidative phosphorylation, was delayed in 4 patients. These findings indicate that in many patients with CHF, exercising muscle has marked metabolic changes consistent with impaired substrate availability and altered biochemistry.

Nutritionally Relevant Supplementation of Vitamin B6 in Lactating Women: Effect on Plasma Prolactin

Pharmacologic doses of vitamin B6 administered to lactating women have been reported to suppress plasma prolactin. As a result, some physicians have recommended restriction of vitamin B6 intake for lactating women. In the present investigation, 20 lactating women were given supplemental doses of vitamin B6, 0.5 to 4.0 mg/d, beginning 24 hours after delivery. Plasma prolactin, plasma pyridoxal phosphate, and breast milk total vitamin B6 concentrations were determined during the first 9 months postpartum. Women receiving the supplement of 4.0 mg compared with 0.5 mg of vitamin B6 per day had significantly higher plasma pyridoxal phosphate (P less than .01) and breast milk total vitamin B6 concentrations (P less than .05) beginning at 1 month postpartum and continuing through the duration of the study. Plasma prolactin concentrations were not significantly different between the two groups. The percentage of all women, regardless of treatment, in whom lactation persisted at 1 and 2 weeks and 1, 3, 6, and 9 months were 100%, 100%, 100%, 90%, 80%, and 65%, respectively. All women who ceased to lactate during the study reported doing so by choice. Nutritionally relevant doses of vitamin B6 elevated plasma pyridoxal phosphate and breast milk total vitamin B6 concentrations of lactating women without reducing plasma prolactin concentration or halting lactation.

Production of pyoverdine, the fluorescent pigment ofPseudomonas aeruginosaPAO1

The nutritional requirements for the production of pyoverdine were studied using Pseudomonas aeruginosa PAO1 in a chemically defined medium, with shaking. Succinic acid and ammonium sulphate were found to be the best sources of carbon and nitrogen for pyoverdine production. The optimum carbon-to-nitrogen ratio was found to be 4:1. Elevated concentrations of phosphate inhibited pyoverdine production.

Uptake of Zn 65 and Mn 54 into body tissues and renal concretions by the Southern Quahog, Mercenaria campechiensis (Gmelin): Effects of elevated phosphate and metal concentrations

The reliable use of marine molluscs as indicator organisms for metal contamination requires an understanding of how environmental parameters effect metal accumulation. 1,2 In Tampa Bay, Florida, phosphate concentrations are periodically extremely high due to local deposits and mining activity. 3 Since an important metal detoxification sink for marine bivalves (inorganic renal granules) requires phosphate, 4,5 its availability may influence metal metabolism. The effects of dissolved phosphate on metal accumulation in marine molluscs are presently undescribed. In this study a subtropical bivalve, Mercenaria campechiensis, is examined for uptake and tissue distribution of Zn 65 and Mn 54 accumulated from seawater containing varied concentrations of inorganic phosphate, total zinc and manganese. Highest 10 day tissue concentrations for both metals were found in the kidney with results showing different uptake patterns for zinc and manganese. Total metal and inorganic phosphate concentrations showed marginal effects on manganese distribution while producing significant variation in the zinc distribution between kidneys and gills.

Intracellular distribution of phosphate in cultured Humulus lupulus cells growing at elevated exogenous phosphate concentrations

The distribution of inorganic phosphate (Pi) between the cytoplasm and the vacuole of Humulus lupulus L. cells grown in suspension culture at different exogenous Pi levels was examined by 31-P nuclear magnetic resonance. In growing cells excess Pi accumulated in the vacuoles and the inhibitory effect of high exogenous Pi was not associated with a change in the cytoplasmic Pi level or with a change in the cytoplasmic pH.

Plasma membrane phosphate transport and extracellular phosphate concentration in the regulation of cellular respiration in isolated perfused rat heart

The role of extracellular P i and transmembrane fluxes across the sarcolemma in the regulation of cellular respiration was studied in isolated Langendorff-perfused rat hearts. Extracellular phosphate did not significantly affect the oxygen consumption or cellular phosphorylation potential of the myocardium. K +-induced arrest was used to change the mechanical work load of the heart. Arresting the heart caused a rapid decrease in the unidirectional efflux of phosphate determined by in vitro prelabelling of the intracellular phosphate compounds with 32P and determining the specific radioactivity of the γ-P of ATP, and the label appearance into the perfusion medium. At normal or elevated perfusate phosphate concentration there was a fairly slow net uptake of phosphate. The decrease in phosphate fluxes upon the K +-induced arrest was probably not due to a decrease in the transmembrane Na + or K + gradients because a further increase in the perfusate K + concentration caused an increase in the K + efflux to the levels observed in contracting hearts. The use of higher than normal concentrations of phosphate necessitated a lowering of the extracellular Ca 2+ concentration, which caused a diminution of the oxygen consumption, accompanied by mitochondrial flavoprotein oxidation in the heart. This finding suggested that the extracellular Ca 2+ concentration may be involved in the substrate level regulation of mitochondrial metabolism.

Compatibility and stability of electrolytes, vitamins and antibiotics in combination with 8% amino acids solution

The compatibility and stability of the following additives in an 8% amino acids and 50% dextrose solution intended for total parenteral nutrition were studied: potassium phosphate, calcium gluconate, magnesium sulfate, multiple vitamine mixtures, folic acid, cyanocobalamin, phytonadione, insulin, ampicillin, cephalothin, kanamycin and gentamicin. In addition to physical examination, techniques of ultraviolet spectroscopy, thin-layer chromatography and microbiologic assay were used to delineate compatibility characteristics. The principle compatibility problems are generated by elevated concentrations of calcium and phosphate. The efficacy of ampicillin, cephalothin and kanamycin in the amino acids/dextrose solution, with or without additives, did not appear to be significantly different from control samples prepared in sterile water. It appeared that gentamicin might be significantly more effective in the test solutions than in sterile water, but further investigation is needed to verify this. A comprehensive study of the stability of vitamins in parenteral nutrient solutions must be made before a final judgment can be made.

Effect of anesthesia and-or hypothermia on cerebral free amino acids in young rats.

AbstractThe whole brain content of glutamic acid significantly decreased in unanesthetized and anesthetized (pentobarbital sodium. 20 mg/kg) 10‐day‐old rats during 90 min hypothermia at 23°C, but not in rats kept equally long at 15°C. The concentration of glutamic acid increased during rewarming to 37°C after 90 min at 23 or 15°C. The concentration of aspartic acid significantly increased during rewarming after 90 min at 23 or 15°C. Rats anesthetized for 10 or 90 min at 37°C had increased cerebral concentrations of leucine and methionine, but the concentrations were significantly lower in rats kept for 90 min at 23°C. During rewarming after 90 min at 23 or 15°C the levels of leucine and methionine increased. The content of ethanolamine phosphate was significantly elevated in rats kept anesthetized for 90 min at 37, 23, or 15°C. An elevated ethanolamine phosphate concentration was found also in unanesthetized rats kept for 90 min at 15°C. Only minor alterations were found in the concentrations of glutamine, glutathione, γ‐aminobutyric acid, taurine, alanine, ethanolamine, glycine, and serine.

Myocardial metabolism in progressive muscular dystrophy.

Myocardial metabolism was studied in 11 patients with progressive muscular dystrophy. Coronary blood flow was measured in four, the cardiac output in six patients. The blood concentrations of oxygen, glucose, inorganic phosphate, pyruvate, and lactate, and the serum activities of malic dehydrogenase and aldolase were determined in simultaneously drawn coronary sinus and arterial blood samples. The cardiac outputs were elevated in all patients. Myocardial extractions of pyruvate and lactate were negative in two patients. Inorganic phosphate concentrations in blood were elevated. Malic dehydrogenase and aldolase were released by the heart in several patients. Differences in oxidation-reduction potential between arterial and coronary venous blood were positive, suggesting glycolysis in the heart muscle. This was accompanied by increased myocardial extraction of glucose. Apparently aerobic glycolysis occurred, since sufficient oxygen was present to account for all glucose extracted. Stimulation of glycolysis by inorganic phosphate was suggested by the relationship between the elevated inorganic phosphate concentration in blood and the myocardial glucose extraction. This suggests the possibility of uncoupling of oxidative phosphorlyation in the myocardium.