Estimates of Na+–K+ pumping in intact canine iliac arteries

1985 ◽  
Vol 63 (2) ◽  
pp. 101-106 ◽  
Author(s):  
P. K. Rangachari
Keyword(s):  
Turnover Rates ◽  
Signal To Noise ◽  
Ouabain Binding ◽  
Iliac Arteries ◽  
Noise Characteristics ◽  
Wet Weight ◽  
Maximal Binding ◽  
External K

Estimates of Na+ pumping capacity were made using Na+-loaded canine iliac arteries. Ouabain-sensitive uptake of 204Tl or 86Rb was used to measure near-maximal pump rates and [3H]ouabain binding to measure the number of pump sites. Compared with Rb+, Tl+ had the higher affinity for the pump and showed better signal-to-noise characteristics. Maximal uptakes were 0.545 μmol∙g−1∙min−1 for Rb+ and 0.40 μmol∙g−1∙min−1 for Tl+ Specific ouabain binding (Kd: 28.62 ± 0.58 nM) was inhibited by external K+, Tl+, and Rb+ and a maximal binding of 51.6 pmol/g wet weight translated into 3.2 × 1013 sites per gram wet weight. Using these values, the maximal values of K+ transported per pump site per minute lie between 7752 and 10562. If each activation of the pump moves 2K+, the turnover rates could lie between 3876 and 5281 per minute.

Cation exchange and glycoside binding in cultured rat heart cells

1979 ◽  
Vol 236 (1) ◽  
pp. C87-C95 ◽  
Author(s):  
D. McCall
Keyword(s):  
Neonatal Rat ◽  
Heart Cells ◽  
Turnover Rates ◽  
Ouabain Binding ◽  
Na Pump ◽  
Mammalian Tissues ◽  
Flux Measurements ◽  
The Mean ◽  
Rat Heart Cells ◽  
K Transport

The Na/K-exchange characteristics, ouabain-binding kinetics, and Na pump turnover rates of synchronously contracting monolayers of neonatal rat myocardial cells were studied. The cells exchange Na rapidly (T1/2 = 35 s) with a mean Na flux of approximately 25 (pmol/cm2)/s. The half time (T1/2) of K exchange is much longer (12 min); the mean K flux is 13 (pmol/cm2)/s. Active Na/K transport, as measured by K influx, is relatively ouabain sensitive, and 10(-6) M ouabain produces half-maximal inhibition. Ouabain (10(-2)M) inhibits 60% of the Na efflux and 75% of the K influx. The cells bind [3H]ouabain rapidly (T1/2 = 8 min), but release it very slowly (T1/2 = 11 h), and both the amount bound and the rate of binding were inversely proportional to extracellular K. Specific [3H]ouabain binding demonstrates saturation reaching a maximum of 1.6 x 10(6) molecules per cell at 2 x 10(-7) M [3H]ouabain. From cell surface area and ouabain-sensitive flux measurements, the Na pump density was calculated at 720/micrometer2 with an individual pump turnover rate of 50/s. Thus the studies indicate that despite their neonatal origin, the behavior of the Na pump in these cells is very similar to that in other mammalian tissues.

Ouabain binding kinetics and FXYD7 expression in astrocytes and neurons in primary cultures: implications for cellular contributions to extracellular K+ homeostasis?

2010 ◽  
Vol 6 (2) ◽  
pp. 127-135 ◽  
Author(s):  
Liang Peng ◽  
Rong Huang ◽  
Shiquen Zhang ◽  
Leif Hertz
Keyword(s):  
Primary Cultures ◽  
Granule Neurons ◽  
Turnover Rates ◽  
Ouabain Binding ◽  
Neuronal Excitation ◽  
Cellular Expression ◽  
Uptake Rates ◽  
The Brain ◽  
Very High

Although Na+,K+-ATPase-mediated K+ uptake into astrocytes plays a major role in re-establishing resting extracellular K+ following neuronal excitation little information is available about astrocytic Na+,K+-ATPase function, let alone mechanisms returning K+ to neurons. The catalytic units of the Na+,K+-ATPase are the astrocyte-specific α2, the neuron-specific α3 and the ubiquitously expressed α1. In the present work, Bmax and KD values for α1, α2 and α3 subunits were computed in cultured cerebro-cortical mouse astrocytes and cerebellar granule neurons by non-linear regression as high-affinity (α2, α3) and low-affinity (α1) [3H]ouabain binding sites, which stoichiometrically equal transporter sites. Cellular expression was also determined of the brain- and α1-β1 isoform-specific FDYX7, regulating Na+,K+-ATPase efficiency and K+-sensitivity. From ouabain-sensitive K+ uptake rates published by ourselves (Walz and Hertz, 1982) or others (Atterwill et al., 1985), Na+,K+-ATPase turnover was determined. Subunits α2 and α3 showed Bmax of 15–30 pmol/mg protein, with maximum turnover rates of 70–80/s. Bmax of the α1 subunit was low in neurons but very high in astrocytes (645 pmol/mg protein), where turnover rate was slow, reflecting expression of selectively expressed FXYD7, and binding was increased by K+. The role of these characteristics for K+ homeostasis are discussed.

An Experimental Study of Lithium Furnace Emission

1978 ◽  
Vol 32 (1) ◽  
pp. 54-56 ◽  
Author(s):  
J. P. Matousek ◽  
L. E. Smythe
Keyword(s):  
Atomic Absorption ◽  
Graphite Furnace ◽  
Growth Curves ◽  
Atomic Emission ◽  
Diagnostic Techniques ◽  
Atomic Absorption Spectrometer ◽  
Signal To Noise ◽  
Absorption Signal ◽  
Noise Characteristics ◽  
Low Levels

Atomic emission of lithium in a small graphite furnace (CRA 63) was observed using a standard atomic absorption spectrometer with simple optical modifications. Improved diagnostic techniques facilitated a study of lithium atomic emission and atomic absorption signal profiles as a function of temperature. Low levels of lithium were measured relatively free from background emission with considerably improved signal-to-noise characteristics. Analytical growth curves plotted in logarithmic coordinates showed only a slight deviation from linearity over a concentration range of three orders.

An evaluation of in vivo voltage-sensitive dyes: pharmacological side effects and signal-to-noise ratios after effective removal of brain-pulsation artifacts

2012 ◽  
Vol 108 (11) ◽  
pp. 2931-2945 ◽  
Author(s):  
T. H. Grandy ◽  
S. A. Greenfield ◽  
I. M. Devonshire
Keyword(s):  
Side Effects ◽  
In Vivo Studies ◽  
Blue Dye ◽  
Single Trial ◽  
Signal To Noise ◽  
Noise Characteristics ◽  
Bpa Removal ◽  
Voltage Sensitive Dyes ◽  
Pulsation Artifacts

In the current study, we investigated pharmacological side effects and signal-to-noise ratios (SNRs) of two commonly used voltage-sensitive dyes (VSDs): the blue dye RH-1691 (1 mg/ml) and the red dye di-4-ANEPPS (0.1 mg/ml), applied in vivo to the rat barrel cortex. Blue dyes are often favored over red dyes in in vivo studies due to their apparent superior SNR, partly because their fluorescence spectrum is farther away from the hemoglobin absorption spectrum, making them less prone to heartbeat-associated brain-pulsation artifacts (BPA). We implemented a previously reported template-based BPA removal algorithm and evaluated its applicability to di-4-ANEPPS before comparing characteristics of the two dyes. Somatosensory-evoked potentials (SEPs) were also recorded. Whereas SEPs recorded before and after application of di-4-ANEPPS failed to exhibit demonstrable differences, RH-1691 caused a significant and prolonged increase in SEP amplitude for several hours. In contrast, neither dye influenced the spontaneous cortical activity as assessed by the spectral content of the EEG. Both dyes turned out to be strikingly similar with respect to changes in fractional fluorescence as a function of SEP response amplitude, as well as regarding shot noise characteristics after removal of the BPA. Thus there is strong evidence that the increased SNR for RH-1691 is a consequence of an artificially increased signal. When applying an appropriate BPA removal algorithm, di-4-ANEPPS has proven to be suitable for single-trial in vivo VSD imaging (VSDI) and produces no detectable neurophysiological changes in the system under investigation. Taken together, our data argue for a careful re-evaluation of pharmacological side effects of RH-1691 and support the applicability of di-4-ANEPPS for stable single-trial in vivo VSDI recordings.

Signal-to-noise characteristics of nonlinear optical amplifiers

2002 ◽  
Author(s):  
R.W. Boyd ◽  
G.S. Agarwal ◽  
W.V. Davis ◽  
A.L. Gaeta ◽  
M. Kauranen ◽  
...  
Keyword(s):  
Nonlinear Optical ◽  
Optical Amplifiers ◽  
Signal To Noise ◽  
Noise Characteristics

scholarly journals Comparison of the side-dependent effects of Na and K on orthophosphate-, UTP-, and ATP-promoted ouabain binding to reconstituted human red blood cell ghosts.

1976 ◽  
Vol 67 (5) ◽  
pp. 527-545 ◽  
Author(s):  
H H Bodemann ◽  
J F Hoffman
Keyword(s):  
Blood Cell ◽  
Adenosine Triphosphate ◽  
Mechanism Of Action ◽  
Red Blood Cell ◽  
Ouabain Binding ◽  
Uridine Triphosphate ◽  
Binding Rate ◽  
External K

This paper is concerned with analyzing the sidedness of action of various determinants which alter the rate of ouabain binding to human red blood cell ghosts. Thus, ouabain binding promoted by orthophosphate (Pi) and its inhibition by Na are shown to be due to inside Pi and inside Na. External K inhibits Pi-promoted ouabain binding and Nao acts to decrease the effectiveness of Ko. Similarly, inside uridine triphosphate (UTPi) stimulates the rate of ouabain binding which can be antagonized by either Nai or Ko acting alone. The actions of Nai and Ko are different when ouabain binding is promoted by Pi and UTPi compared to inside adenosine triphosphate (ATPi). With ATPi, the ouabain binding rate is only affected when Nai and Ko are both present. Possible differences in the mechanism of action of K and Na on Pi-and UTP-promoted binding are discussed in the light of their sidedness of action.

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