Liquid Scintillation Counting of Doubly-Labeled Samples.  Choice of Counting Conditions for Best Precision in Two-Channel Counting.

Bush, E.T.

doi:10.1021/ac60212a039

Cited by 53 publications

(10 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The separation of 8H and MCl-counts was optimized using the method of Bush (1964). The cellular concentrations are given as the concentration in cell water after correction for trapped volume ([(H] inulin space) in the cell pellets.…”

Section: Measurement Of Ion Concentrationsmentioning

confidence: 99%

Membrane potential, chloride exchange, and chloride conductance in Ehrlich mouse ascites tumour cells.

Hoffmann¹,

Simonsen²,

Sjøholm³

1979

The Journal of Physiology

109

View full text Add to dashboard Cite

SUMMARY1. The steady-state tracer exchange flux of chloride was measured at 10-150 mM external chloride concentration, substituting either lactate or sucrose for chloride. The chloride flux saturates in both cases with a K1 about 50 and 15 mm, respectively.2. The inhibitory effect of other monovalent anions on the chloride transport was investigated by measuring the 3601-efflux into media where either bromide, nitrate, or thiocyanate had been substituted for part of the chloride. The sequence of increasing affinity for the chloride transport system was found to be: Br-< Cl1 < SCN-= NO3-.3. The chloride steady-state exchange flux in the presence of nitrate can be described by Michaelis-Menten kinetics with nitrate as a competitive inhibitor of the chloride flux.4. The apparent activation energy (EA) was determined to be 67 + 6-2 kJ/mole, and was constant between 7 and 38 0C.5. The membrane potential (Vm) was measured as a function of the concentration of external K+, substituting K+ for Na+. The transference number for K+ (tK) was estimated from the slope of Vm vs. log10 (K+)e, and tcl and tNa were calculated, neglecting current carried by ions other than Cl-, K+, and Na+. The diffusional net flux of K+ was calculated from the steady-state exchange flux of 42K+, assuming the flux ratio equation to be valid. From this value the K+ conductance and the Na+ and Cl-conductances were calculated. The experiments showed that %t, GN., and GK are all about 14 ,US/cm2. 6. The net (conductive) chloride permeability derived from the chloride conductance was 4 x 10-8 cm/sec compared with the apparent permeability of 6 x 10-7 cm/ sec as calculated from the chloride tracer exchange flux. These data suggest that about 95 % of the chloride transport is mediated by an electrically silent exchange diffusion.7. Comparable effects of phloretin (0.25 mM) on the net (conductive) permeability and the apparent permeability to chloride (about 80 % inhibition) may indicate that the chloride exchange and conductance pathways are not completely separate and Experiments were performed at both addresses.

show abstract

Section: Measurement Of Ion Concentrationsmentioning

confidence: 99%

Membrane potential, chloride exchange, and chloride conductance in Ehrlich mouse ascites tumour cells.

Hoffmann¹,

Simonsen²,

Sjøholm³

1979

The Journal of Physiology

109

View full text Add to dashboard Cite

show abstract

“…The cells were lysed in 2 mlO.270 (wiv) sodium dodecyl sulfate (SDS) and the entire lysate counted in 7 ml Aquasol. Seintillation spectrometer settings for double-label counting were as described by Bush (1964). In calculation of hexose uptake, L4C-sucrose served as a correction for trapped extracellular medium.…”

Section: Methodsmentioning

confidence: 99%

Cyclic AMP does not modulate hexose uptake of serum‐deprived BHK‐21 fibroblasts

Lavis¹,

Davenport

Pontier

et al. 1982

Journal Cellular Physiology

View full text Add to dashboard Cite

We have studied the uptakes of the glucose analogs, 2-deoxyglucose (2DG), and 3-O-methylglucose (3OMG) in serum-deprived BHK-21 fibroblasts. Incubation for 4 hours with 0.25 mM 1-methyl-3-isobutylxanthine (MIX) increased cellular cyclic AMP 3 to 15 fold, without affecting the initial rates of uptake of these sugars. Incubation with 100 nM insulin, doubled hexose uptake without affecting cyclic AMP. Insulin did not modify the cyclic AMP response to MIX; nor did MIX alter the hexose uptake response to insulin. There was no effect of 0.1 mM L-isoproterenol (ISO) or 0.1 mM prostaglandin E1 (PGE1) on cyclic AMP. PGE1 slightly stimulated uptake of 2DG but not 3OMG; ISO did not affect hexose uptake. We conclude that cyclic AMP does not directly regulate hexose uptake in these cells.

show abstract

“…In the tritium channel, both tritium and 14C are counted, but with different efficiencies. A discussion of the optimization of counting conditions to maximize precision of counting doubly labeled samples can be found in Bush's paper (9).…”

Section: Estimates Of Basic Variancesmentioning

confidence: 99%

Analysis of data from experiments using double labelling

Jacquez¹,

Foster²,

Shanahan³

1978

Analytical Biochemistry

View full text Add to dashboard Cite

Frequently as a result of experiments in which two isotopes are used one is left with a sequence of samples, the ratio of labeling in each sample, and the problem of analyzing the ratios. Suppose that the experiments are designed so that one expects uniform labeling except for one or two special groups of samples. The problem, then, is to find these groups. Because of the variability in the count rate from sample to sample, the variance of the ratios differs from sample to sample making statistical analysis difficult. Furthermore, there is significant serial correlation in the sample disintegrations per minute for each of the isotopes. We have found that the serial correlation in the labeling ratio is small and of questionable significance in controls but becomes significant when there is a subsequence of samples in which the labeling ratio differs from that in the remainder of the gel. We examine the analysis of variance as a test for significant deviations in the labeling ratio and suggest a method for plotting deviations of labeling ratio from the average background labeling ratio. Finally, we develop a method of estimating the mean labeling ratio from the regression of disintegrations per minute of one isotope on those of the other isotope. This provides another way of plotting deviations in labeling ratio in terms of the residuals around the line of regression.

show abstract

Liquid Scintillation Counting of Doubly-Labeled Samples. Choice of Counting Conditions for Best Precision in Two-Channel Counting.

Cited by 53 publications

References 5 publications

Membrane potential, chloride exchange, and chloride conductance in Ehrlich mouse ascites tumour cells.

Membrane potential, chloride exchange, and chloride conductance in Ehrlich mouse ascites tumour cells.

Cyclic AMP does not modulate hexose uptake of serum‐deprived BHK‐21 fibroblasts

Analysis of data from experiments using double labelling

Contact Info

Product

Resources

About