Root cortical aerenchyma (RCA) is induced by hypoxia, drought, and several nutrient deficiencies. Previous research showed that RCA formation reduces the respiration and nutrient content of root tissue. We used SimRoot, a functional-structural model, to provide quantitative support for the hypothesis that RCA formation is a useful adaptation to suboptimal availability of phosphorus, nitrogen, a...

Sodium and potassium influxes and outfluxes have been studied in single isolated muscle fibers from the giant barnacle both by microinjection and by external loading. The sodium influxes and outfluxes were 49 and 39 pmoles /cm(2)-sec (temperature = 15-16 degrees C) respectively. The potassium influxes and outfluxes were 28 and 60 pmoles/cm(2)-sec (temperature = 13-16 degrees C) respectively. Re...

In frog twitch muscle fibres, Na-octanoate (NaC8) shifted the relation between potassium induced tension and membrane potential to the right. The present study has been carried out to investigate the effect of this fatty acid on frog tonic fibres. Potassium contractures measured on bundles of 30-40 fibres of ileofibularis muscles were less decreased by NaC8 (2.5-10 mmol/l) than those of twitch ...

The advent of a new method for measuring the zeta potential of planar surfaces, the rotating disk, allowed the investigation of the charging process of mica after immersion in water. The zeta potential of freshly cleaved muscovite mica was recorded within seconds of immersion of the sample and in fractions of a second thereafter. The zeta potential of mica in water at pH = 5.6 with no added pot...

this study was conducted to investigate the effects of planting date, foliar application of benomyl fungicide and potassium silicate in improving the quality of soybean (cv. williams) seed in gorgan during 2011 and 2012. in the first year (2011), the experimental treatments were including planting dates (april 20, may 13, june 3, june 29 and july 22) and foliar application of benomyl fungicide ...

"Low sodium" muscles were prepared which contained around 5 mmoles/kg fiber of intracellular sodium. "High sodium" muscles containing between 15 and 30 mmoles/kg fiber of intracellular sodium were also prepared. In low sodium muscles application of 10(-5)M strophanthidin reduced potassium influx by about 5%. Potassium efflux was unaffected by strophanthidin under these conditions. In high sodiu...

Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10...

1. In erythrocytes, the extrusion of a cell sodium load is accomplished by the ouabain-sensitive sodium-potassium pump and by the frusemide-sensitive sodium-potassium cotransport, which operate against the passive sodium permeability. All these three components of the cell sodium balance were studied in essential hypertension (410 subjects were investigated). 2. An abnormally low rate of net so...

Rice (Oryza sativa L.) requires adequate potassium (K) nutrition for optimal growth, grain yield, and disease resistance. Studies were conducted in 2001 and 2002 at the Pine Tree Branch Experiment Station (PTBS) to characterize K uptake by rice and investigate the effect of both K-fertilizer application rate and time on rice growth, K uptake, and grain yield. Potassium fertilizer was applied at...

Thirteen children with hyperkalaemia were treated by intravenous infusions of salbutamol, 4 micrograms/kg over 20 minutes. Reductions in the mean (SD) plasma potassium concentrations, of 1.48 (0.5) and 1.64 (0.5) mmol/l were obtained at 40 and 120 minutes, respectively, after completion of the infusions. No side effects were noted.