The effect of ouabain on water diffusion in the rat hippocampal slice measured by high resolution NMR imaging

Buckley, David L.; Bui, Jonathan D.; Phillips, M. Ian; Zelles, Tibor; Inglis, Benjamin A.; Plant, H. Daniel; Blackband, Stephen J.

doi:10.1002/(sici)1522-2594(199901)41:1<137::aid-mrm19>3.0.co;2-y

Cited by 93 publications

(118 citation statements)

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“…The expression (1 Ϫ s 13o Ϫ s 132 ) in Eq. [3] is thus the fraction of particles which stay at node 1 during the time step. Note that Eq.…”

Section: Finite Difference Diffusion Simulation Methodsmentioning

confidence: 99%

“…Note that Eq. [3] explicitly defines the updated concentrations only in terms of the concentrations at the previous time step, and therefore does not require solving a system of equations. Further, if node 1 and node 2 are separated by a permeable membrane or layers of myelin sheaths, the jump probabilities between these nodes have to be modified as…”

Section: Finite Difference Diffusion Simulation Methodsmentioning

confidence: 99%

“…Variations in membrane permeability usually have been discounted as a possible cause for the mismatch between diffusion component fractions and cellular volume ratios (1,3,4). To examine a possible dependence of the diffusion behavior on membrane permeability, we performed diffusion simulations (in the x direction) by varying the permeability of both the axonal membrane and myelin sheath between 0.1 and 0.001 m/ms.…”

Section: Effect Of Water Exchange and Membrane Permeabilitymentioning

confidence: 99%

“…Biexponential NMR diffusion attenuation of water has been reported in both the brain (1)(2)(3)(4) and the spinal cord (5)(6)(7), and the phenomenon appears to be inherent to all neural tissues. The observation has invariably been attributed to the presence of two different fractions corresponding to fast and slow apparent diffusion, associated with the volume fractions of extracellular spaces (ECS) and intracellular space (ICS).…”

mentioning

confidence: 99%

“…Toward this goal, NMR diffusion attenuation was simulated on the basis of optical images derived from sections of fixed rat spinal cord for a pulsed gradient spin-echo (PGSE) sequence. Specifically, we intended to examine the various hypotheses advanced in earlier studies (1)(2)(3)(4)7) to reconcile the observed diffusion fractions with actual tissue compartment fractions.…”

mentioning

confidence: 99%

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Biexponential diffusion attenuation in the rat spinal cord: Computer simulations based on anatomic images of axonal architecture

Chin

Wehrli

Hwang

et al. 2002

Magnetic Resonance in Med

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Water diffusion in neurological tissues is known to possess multicomponent diffusion behavior. The fractions of fast and slow apparent diffusion components have often been attributed to the volume fractions of extracellular space (ECS) and intracellular space (ICS) although diffusion fractions are at variance with the tissue compartment volume ratios. In this article this puzzle was examined with a finite difference diffusion simulation model on the basis of optical images from sectioned rat spinal cord. Here the results show that assignment of fractions obtained from biexponential fits of fast and slow diffusion attenuation to ECS and ICS volume ratios is not correct. Rather, the observed multicomponent diffusion behavior is caused by motional restriction and limited intercompartmental water exchange in that at long diffusion times diffusion attenuation is shown to become monoexponential. Although the measured apparent diffusion fractions also depend on T 2 relaxation time of water protons in the various compartments, the sensitivity to T 2 is small and thus Biexponential NMR diffusion attenuation of water has been reported in both the brain (1-4) and the spinal cord (5-7), and the phenomenon appears to be inherent to all neural tissues. The observation has invariably been attributed to the presence of two different fractions corresponding to fast and slow apparent diffusion, associated with the volume fractions of extracellular spaces (ECS) and intracellular space (ICS). However, the discrepancies between the actual ECS and ICS volume ratios and the calculated fractions of fast and slow diffusion components remain unresolved.Biexponential water diffusion in both normal and ischemic rat brains was observed by Niendorf et al. (1). Based on the results of cell swelling and shrinking experiments and findings from electrical impedance measurements, the authors observed changes in the fractions of fast and slow diffusion components which were correlated with changes in the volume fractions of the ECS and ICS. However, the two fractions were found to deviate significantly from those of intra-and extracellular compartment volumes.Ignoring effects of internal gradients and their interaction with the external diffusion-sensitizing gradients, the differences between intra-and extracellular T 2 relaxation times, partial volume averaging, and water exchange between the intra-and extracellular compartments were considered to explain this discrepancy. Biexponential diffusion behavior in rat brain was described by Buckley et al. (3), who found that cell swelling induced by ouabain resulted in an increase in the fraction corresponding to the slow component. The mismatch between the expected apparent diffusion component fractions and physiological compartments was attributed to differences in T 2 relaxation times between ECS and ICS. Very recently, Inglis et al. (7) reported diffusion tensor data for fast and slow diffusion in rat spinal cords. Two components were observed in both gray matter and white matter, and the slow com...

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“…The expression (1 Ϫ s 13o Ϫ s 132 ) in Eq. [3] is thus the fraction of particles which stay at node 1 during the time step. Note that Eq.…”

Section: Finite Difference Diffusion Simulation Methodsmentioning

confidence: 99%

Section: Finite Difference Diffusion Simulation Methodsmentioning

confidence: 99%