87-Rubidium NMR: A novel method of measuring cation flux in intact kidney

Endre, Zoltán H.; Allis, Jonathan L.; Ratcliffe, Peter J.; Radd, G K

doi:10.1038/ki.1989.117

Cited by 20 publications

(22 citation statements)

References 13 publications

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“…750 Hz wide, as compared to the linewidth in free solution of approximately 150 Hz. We were able to show that the spectrum was com posed of broad (approximately 900 Hz) and narrow (approximately 150 Hz) Lorentzian components, localised to the intra-and extra cellular compartments, respectively [6,16]. The visibility of renals Rb+ was determined by comparing the NMR-detectable amount of s Rb+ with that determined in the same experi ments by radioactive S7Rb+ measurements [6].…”

Section: Rubidium Nmrmentioning

confidence: 99%

“…In preliminary experiments on s7Rb* up take by the perfused rat kidney, at 4.2T, we noted considerable broadening of the spec trum with time [5,6,16], Figure 3 shows a typical NMR spectrum obtained after 90 min of perfusion with Krebs-Henseleit buffer con taining 0.59 mAf R b '. The high frequency Rb7 peak is a reference, consisting of 1 M Rbl in saturated KI.…”

Section: Rubidium Nmrmentioning

confidence: 99%

“…We have developed R 7Rb NMR spectrosco py as a means of measuring K~ flux in kidney [5,6], erythrocytes [7], muscle [8] and heart [9]. Table 1 compares the physical NMR prop erties of 39K and s7Rb.…”

Section: Rubidium Nmrmentioning

confidence: 99%

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87Rb, 23Na and 31P Nuclear Magnetic Resonance Spectroscopy of the Perfused Rat Kidney

Allis¹,

Endre²,

Radda³

1989

Kidney Blood Press Res

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⁸⁷Rb, ²³Na and ³¹P nuclear magnetic resonance (NMR) were used to monitor changes in renal cations and energetics during the induction of hypoxia in the isolated perfused rat kidney. The NMR-determined unidirectional Rb⁺ flux in normoxic kidneys was shown to be a good measure of net intracellular K⁺ influx in the perfused rat kidney model. The changes in ⁸⁷Rb, ²³Na and ³¹P spectra following the induction of hypoxia are consistent with hypoxic depletion of intracellular adenosine triphosphate (ATP) and a subsequent decrease in Na-K-ATPase transport activity. The exponential rate constant for ⁸⁷Rb⁺ efflux measured during Rb⁺ uptake in normoxic kidneys (0.12 ± 0.01 min¹) was not significantly different to the rate constant for ⁸⁷Rb⁺ efflux during the induction of hypoxia (0.16+0.07 min^-1). We conclude that there is no direct effect of hypoxia on renal cellular membrane integrity and that renal cell sensitivity to hypoxia is due to an inability to sustain cellular ion gradients following depletion of intracellular ATP.

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Section: Rubidium Nmrmentioning

confidence: 99%

Section: Rubidium Nmrmentioning

confidence: 99%

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87Rb, 23Na and 31P Nuclear Magnetic Resonance Spectroscopy of the Perfused Rat Kidney

Allis¹,

Endre²,

Radda³

1989

Kidney Blood Press Res

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“…[40][41][42] Later on, 87 Rb visibility was re-evaluated and found to be close to 100%. 43,44 Early studies Pioneering studies on 87 Rb MRS applications in mammalian systems, such as red blood cells (RBC) 45,46 , kidney 37,42,47 , heart 41 and skeletal muscle 40 were performed by the G.K. Radda group in the late 1980s. Human RBC Rb þ uptake kinetics in the presence of shift reagent, 25 mM Dy-TTHA, were evaluated and unidirectional K þ uptake rates were calculated.…”

Section: Nmr Properties Of Natural Rb Isotopesmentioning

confidence: 99%

“…15,16 For example, shortening of AP is typically associated with activation of K þ channels. 15,16 In cell suspensions and multicellular preparations radioisotope techniques utilizing 42 K, 86 …”

Section: K þ Transport In Cardiac Cellsmentioning

confidence: 99%

Rubidium-87 magnetic resonance spectroscopy and imaging for analysis of mammalian K+ transport

Kupriyanov¹,

Gruwel²

2005

NMR Biomed.

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Kinetics of ATP-sensitive K+ channels in isolated rat hearts assessed by87Rb NMR spectroscopy

et al. 1998

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An experimental model was developed to evaluate the effects of activators and inhibitors of KATP channels on unidirectional K+ fluxes in the whole heart. Isolated rat hearts perfused in the Langendorff mode were equilibrated with Pi‐free Krebs– Henseleit buffer (KH buffer) containing 0.94– 2.14 mM RbCl and 3.76 mM KCl (20– 36% of K+ substituted by Rb+). Rb+ efflux was initiated by removing Rb+ from the perfusate and 87Rb spectra were acquired continuously with a 1– 2 min time resolution. In hearts with normal energetics, the efflux of Rb+ fit a monoexponential function, and the rate constant did not depend on intracellular [Rb+]. Agents depressing excitability and heart rate (HR), such as 0.6 mM lidocaine (Lido), 10 μ M carbachol (carb) and 20 mM MgSO4, inhibited Rb+ efflux such that the rate constant, k (103/min), decreased from 50 ± 1.2 in the beating heart to 26 ± 1, 40 ± 1.1 and 19 ± 1.2, respectively. In contrast, high [K+] (21 mM) did not affect the k value (50 ± 4.5), independently of the presence or absence of bumetanide (Bum, 30 μ M) and glibenclamide (Glib, 5 μ M). Dinitrophenol (DNP, 0.2 mM) added in the presence of high [K+] + Bum increased k three‐fold, to 160 ± 5. This effect was associated with a significant decrease in phosphocreatine (PCr, <10% of initial) and ATP (≃ 15%) levels, and a 7‐fold increase in the Pi level, assessed by 31P‐NMR spectroscopy. Glib completely reversed the effect of DNP. Pinacidil (Pin, 20‐80 μ M) did not affect the k value either in beating control hearts or in the presence of Carb or KCl + Bum. Moreover, under conditions of moderate metabolic stress induced by 0.05 mM DNP (PCr, 35%; ATP, 65%), where half‐maximal activation of KATP channels occurred, Pin did not further activate Rb+ efflux. We conclude that:(1) heart rate‐independent Rb+ efflux accounts for 40– 80% of the total Rb+ efflux in beating (300 bpm) rat hearts;(2) DNP‐activated Rb+ efflux is a good model for testing inhibitors of KATP channels in whole hearts; and (3) Pin is not an effective KATP channel opener in the rat heart model. © 1998 John Wiley & Sons, Ltd.

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87-Rubidium NMR: A novel method of measuring cation flux in intact kidney

Cited by 20 publications

References 13 publications

<sup>87</sup>Rb, <sup>23</sup>Na and <sup>31</sup>P Nuclear Magnetic Resonance Spectroscopy of the Perfused Rat Kidney

<sup>87</sup>Rb, <sup>23</sup>Na and <sup>31</sup>P Nuclear Magnetic Resonance Spectroscopy of the Perfused Rat Kidney

Rubidium-87 magnetic resonance spectroscopy and imaging for analysis of mammalian K+ transport

Kinetics of ATP-sensitive K+ channels in isolated rat hearts assessed by87Rb NMR spectroscopy

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